Linear cardiac assist pulsatile pump

ABSTRACT

Described herein are pumps that linearly reciprocate to assist with circulating blood within the body of a patient. Red blood cell damage may be avoided or minimized by such linear pump movement. The linearly reciprocating movement may also generate a pulsatile pumping cycle that mimics the natural pumping cycle of the heart. The pumps may be configured to reside at various body locations. For example, the pumps may be situated within the right ventricle, the left ventricle, the ascending aorta, the descending aorta, the thoracic aorta, or the abdominal aorta. In some instances, the pump may reside outside the patient.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/923,542, filed on Oct. 19, 2019, and U.S. Provisional Application No.63/044,298, filed on Jun. 25, 2020, each of which is hereby incorporatedby reference in its entirety.

FIELD

This application relates generally to blood pumping devices. The devicesmay be cardiac assist devices or cardiac assist pumps of the type usedto supplement or sustain blood flow on a short-term basis. Such devicesare generally utilized in the treatment of patients experiencingcompromised heart performance or heart failure in order to stabilize thepatient and gain time for implementing more long-term treatment.

BACKGROUND

The treatment and survivability of patients experiencing severe hearttrauma or heart failure is typically a time critical process. In mostcases, the treatment of patients experiencing traumatic heart failurerequires immediate life-sustaining measures. Basically, medicalpersonnel must initially assist or stabilize the failing heart tomaintain systemic circulation until further diagnostic measures aretaken or treatment options decided.

While in some instances it may be possible for medical practitioners tostabilize such patients through careful administration of various drugs,the stabilization process often requires the application of asupplemental blood pumping apparatus. Such supplemental blood pumpingapparatuses, known generally in the art as “cardiac assist devices” or“cardiac assist pumps” have had limited success despite the availabilityof various designs. These cardiac assist pumps generally utilize a smallpumping apparatus, which is combined with a catheter support operativelycoupled to an external pump drive and pump control system. The objectiveis to insert the pump into the patient's blood flow at a critical pointin order to supplement or substitute for the pumping action of thepatient's heart. While various pump design approaches have beenemployed, most cardiac assist pumps that have been developed include arotary type pump such as a turbine impeller or the like.

Unfortunately, rotary type pumps have proven to be problematic forseveral reasons. Perhaps the most critical limitation of such pumpsresults from their undesired high speed of operation.Characteristically, such rotary pumps are required to be operated athigher rotational speeds in order to provide sufficient pressure andblood flow. Another drawback is that the use of high rotational speedpumps such as turbines, even on a short-term basis, causes damage to thepatient's blood cells, which in turn endangers the patient's life. As aresult, the operating time of cardiac assist pumps employing arotational, turbine type pumping apparatus is typically limited. Inaddition to blood cell damage caused by high speed rotating pumpapparatuses, problems also arise due to the constant unvarying flowcharacteristics of such rotational pumps. It has been found that theconstant draw of a rotating pump may interfere with the action of heartvalves and the pumping action of the heart.

Accordingly, it would be beneficial to have improved cardiac pumpdevices that avoid excessive damage to blood cells, and which arecompatible with the pulsatile blood flow and pumping characteristics ofthe human heart.

SUMMARY

Described herein are pumps that linearly reciprocate to assist withcirculating blood within the body of a patient. Red blood cell damagemay be avoided or minimized by such linear pump movement. The linearlyreciprocating movement may also generate a pulsatile pumping cycleresulting in a pulsatile blood flow that is compatible with theoperation of the patient's heart. The pumps may be configured to resideat various body locations. For example, the pumps may be situated withinthe right ventricle, the left ventricle, the ascending aorta, thedescending aorta, the thoracic aorta, or the abdominal aorta. In someinstances, the pump may reside outside the patient.

In general, the pumps for assisting blood circulation described hereinmay include an expandable housing and a valve member disposed within theexpandable housing that linearly reciprocates therein. The valve membermay be, for example, a flexible diaphragm or a valve cone. Additionally,the valve members may include an inlet side that faces the inlet of theexpandable housing, and an outlet side that faces the outlet side of theexpandable housing. The expandable housing may include an interiorsurface and an expanded configuration, and may define a chamber forcollecting blood. The flexible diaphragm may have an extendedconfiguration and a collapsed configuration, and may include a diaphragmbody and a rim. The valve cone may have an expanded configuration and acollapsed configuration, and may include a layer having a plurality offlaps that allow blood flow through the valve cone into the housingduring the fill stroke, but which prevent blood flow through the valvecone during the pump stroke. In some instances, the pumps include ahousing that is not expandable.

The valve members may be coupled to a support element having an expandedconfiguration and a collapsed configuration. The valve members may bestructured such that expansion of the support element transforms thevalve members to their expanded or extended configurations. In somevariations, the support element may be an expandable frame having aconical shape. The expandable frame may be coupled to the actuator, andmay support the valve cone or the flexible diaphragm as it linearlyreciprocates within the housing. In other variations, the supportelement may be a tine support comprising a base and a plurality of tinescoupled to the actuator that support the flexible diaphragm in theextended configuration during the pump stroke. The plurality of tinesmay be flexible and/or resilient, and have an expanded configuration anda compressed configuration.

The pumps may include an actuator coupled to the valve members (e.g.,the flexible diaphragm or the valve cone), which may be configured tolinearly reciprocate the valve members within the expandable housing togenerate a fill stroke and a pump stroke of a pumping cycle. The rim ofthe valve members may be configured to maintain contact with theinterior surface of the expandable housing during the pump stroke. Insome variations, contact may be maintained for the entire duration ofthe pump stroke. In other variations, contact may be maintained for aportion of the pump stroke, as long as sufficient pressure is generatedto move the desired amount of blood out of the housing during the pumpstroke. In further variations, for example, when high pump speeds arerequired, the valve members may be configured such that there is aslight clearance or gap between the rim and the interior surface of thehousing. The clearance gap may help to avoid the creation of unduefriction in the pump. The clearance gap may also be sized so thatadequate pressure may be generated for the pump stroke while alsoavoiding crushing or damaging red blood cells during the pump stroke.Here the diameter of the valve members in their extended or expandedconfigurations may be at least about 95 percent of the diameter of thehousing in its expanded configuration. For example, the valve members intheir extended or expanded configurations may be at least about percent95 percent, at least about 96 percent, at least about 97 percent, atleast about 98 percent, or at least about 99 percent of the diameter ofthe housing in its expanded configuration. The pumps may be driven by anexternal linear motor drive and linear motor controller situated at theend of a catheter external to the patient. The linear motor drive may beoperatively coupled to the linearly acting cardiac assist pump by aflexible cable or other flexible actuator. A movable sleeve or sheathmay hold the expandable housing and diaphragm or valve cone in acollapsed configuration to enable their insertion and advancement to atarget location within the circulatory system.

More specifically, the expandable housing of the pump may comprise asupport or scaffold including a proximal end and a distal end. Thescaffold may be made from a material comprising stainless steel,titanium, or alloys thereof. With respect to the proximal and distalends, they may or may not be tapered. Furthermore, the distal end of thescaffold may include an inlet for blood flow during the pump stroke. Theproximal end of the scaffold may include an outlet for blood flow duringthe pump stroke.

In the expanded configuration, the expandable housing may have adiameter ranging from about 12 mm to about 20 mm. The expandable housingmay further include a covering. For example, the expandable housing mayinclude a polymer layer, which may comprise an elastomeric polymer suchas, but not limited to, a silicone, a polyester, a polyurethane, or acombination thereof. Alternatively, the expandable housing may include afabric layer coupled to the scaffold. For example, the fabric layer maycomprise a woven material such as buckram or a material woven frompolyester fibers. A film or sheet of non-woven material such as Mylar®plastic film may also be coupled to the expandable housing.

The pump may further include a cannula extending from the expandablehousing. The cannula may extend from either the proximal end or thedistal end of the expandable housing. The length of the cannula mayvary, depending on such factors such as the intended location of pumpplacement, or the age or size of the patient. For example, cannulalengths may range from about 2.5 cm to about 5.0 cm, about 25 cm toabout 30 cm, or about 35 cm to about 40 cm.

When the pump includes a valve cone within the expandable housing, thevalve cone may include a plurality of material layers coupled to anexpandable frame. The plurality of material layers may include meshlayers, flow control layers, or a combination thereof. In someinstances, a mesh layer may be disposed between a flow control layer andthe expandable frame. Woven fabrics or elastomeric polymers may be usedto form the mesh layer. Exemplary elastomeric polymers include withoutlimitation, a silicone, a polyester, a polyurethane, or a combinationthereof. The material layers may be coupled to the expandable frame inany suitable manner, for example, by stitching, suturing, orembroidering, by use of an adhesive, by heat sealing, or by welding. Theexpandable frame may comprise stainless steel, nickel, titanium, oralloys thereof. In general, the valve cone has a conical shape, but anyshape capable of being collapsed to permit advancement through thecannula may be used. When the valve cone is conically shaped, theplurality of material layers (e.g., the mesh and flow control layers)and the expandable frame in their expanded configurations are conicallyshaped. As previously mentioned, the valve cone may have an inlet sidethat faces the inlet of the expandable housing, and an outlet side thatfaces the outlet of the expandable housing.

The flow control layer of the valve cone may also be formed from variouspolymers, for example, an elastomeric polymer as stated above, or fromMylar® plastic film. The flow control layer may include a plurality offlaps having an open configuration and a closed configuration. Ingeneral, the plurality of flaps are in the open configuration during thefill stroke, and in the closed configuration during the pump stroke. Theflow control layer may be cut to create a plurality of flaps, which maybe of any suitable size and shape that allows blood to flow into thehousing during the fill stroke. For example, the flaps may have asemi-circular shape, an arc shape, a circular shape, a triangular shape,a diamond shape, a square shape, or a rectangular shape. Any suitablenumber of flaps in the flow control layer may also be employed. Forexample, a flow control layer including 15 flaps may be useful. Thevalve cone may be configured such that a greater number of flaps areincluded when they are smaller in size, and a smaller number of flapsare included when they larger in size. When the flaps are semi-circularin shape, they may have a radius ranging from about 0.50 mm to about 3.0mm, including all values and sub-ranges therein.

The mesh layer may be used to support the flow control layer such thatwhen pressure against the flaps is applied during the pump stroke, theflaps are not pushed through the openings in the expandable frame. Thus,the mesh layer may help maintain the flaps in the closed configurationduring the pump stroke when blood is moved out of the housing via thehousing outlet. However, during the fill stroke, the mesh layer permitsblood to flow from the housing inlet through the holes in the mesh andthen through the flaps, transitioning them to their open configurationso that blood may move to the outlet side of the valve cone. In someinstances, for example, when the openings of the expandable frame aresmaller than the flaps, the valve cone may not include a mesh layer.

In addition to a rim, the flow control layer may include a body. Thebody and the rim may be made from the same material or from differentmaterials. Additionally, the body and the rim may be separate componentsor integrally formed with one another. When provided as separatecomponents, the body may be formed from an elastomeric polymer or fromMylar® plastic film, and the rim may be an O-ring. The peripheral edgeof the flow control layer may be rolled over the O-ring to form the rim.The thickness of the rim may be greater than the thickness of the body.The body may have a thickness ranging from about 0.03 mm to about 0.05mm. The rim may have a thickness ranging from about 0.20 mm to about 1.5mm.

The flexible diaphragm contained within the expandable housing maycomprise an elastomeric polymer. Non-limiting examples of elastomericpolymers include silicone, polyester, polyurethane elastomers, or acombination thereof. The body and rim of the flexible diaphragm maycomprise the same material or different materials. In some instances,the diaphragm body and rim are integrally formed. Thicknesses of thediaphragm body may range from about 0.03 mm to about 0.3 mm. Withrespect to the rim of the diaphragm, its thickness may range from about0.70 mm to about 1.5 mm. The thickness of the rim may be greater thanthe thickness of the diaphragm body, which may allow the flexiblediaphragm to be in its collapsed configuration during the fill stroke,and the extended configuration during the pump stroke of a pumpingcycle. However, in some variations, the rim and body may have equalthicknesses. The rim of the flexible diaphragm may have a width rangingfrom about 1 mm to about 2 mm.

Furthermore, the flexible diaphragm may have any suitable shape orgeometry capable of creating a seal between the rim of the diaphragm andthe interior surface of the expandable housing during the pump stroke.For example, the flexible diaphragm may have a conical shape when in theextended configuration. A plurality of ribs that extend from a centerportion of the diaphragm body to the rim may be employed to maintain theconical shape during a pump stroke. The plurality of ribs may have a ribangle between a rib of the plurality of ribs and an axis perpendicularto the actuator that ranges from about 30 degrees to about 60 degrees.The plurality of ribs may be equally spaced from one another. In somevariations, the plurality of ribs may have unequal spacing from oneanother. Some variations of the pump may also include a tine supportcomprising a base and a plurality of tines coupled to the actuator thatsupport the flexible diaphragm in the extended configuration during thepump stroke. The plurality of tines may be flexible and/or resilient,and have an expanded configuration and a compressed configuration. Inother variations, the flexible diaphragm may be coupled to an expandableframe that is conically shaped. Coupling to the expandable frame may beaccomplished in any suitable manner, for example, by stitching,suturing, or embroidering, by use of an adhesive, by heat sealing, or bywelding.

In some instances, the expandable housing of the pump may include aplurality of openings or perforations. The number of openings utilizedmay range between about 2 to about 25. The openings may be equally orunequally spaced on a portion of the expandable housing. Additionally,the plurality of openings may have a diameter ranging between about 0.10mm to about 6.50 mm. When the expandable housing includes openings, askirt may also be coupled to the expandable housing that surrounds theplurality of openings.

There are some variations in which the pump may be disposed within aconsole external to a patient. A coaxial catheter coupled the housing ofthe pump may provide continuous and pulsatile blood flow between thepatient and the external pump, and have a diameter between about 1° F.and 18F. The coaxial catheter may include an inflow lumen and an outflowlumen. The inflow lumen may generally have a diameter greater than about5 F.

Methods for pumping blood are further described herein. The methodsgenerally include advancing a pump to a target location within thecirculatory system of a patient, where the pump includes an expandablehousing comprising an interior surface, an expanded configuration, and acollapsed configuration. The pump may further include a valve memberthat linearly reciprocates within the housing. Exemplary valve membersmay be a valve cone including a plurality of material layers coupled toan expandable frame, or a flexible diaphragm. The valve cone andflexible diaphragm may comprise a body and a rim, where the valve conehas an expanded configuration and a collapsed configuration, and theflexible diaphragm has an extended configuration and a collapsedconfiguration. Once at the target location, the expandable housing maybe expanded to the expanded configuration and the valve cone or flexiblediaphragm contained therein linearly reciprocated to generate a fillstroke and a pump stroke of a pumping cycle. During the pump stroke,contact between the rim of the valve cone or flexible diaphragm and theinterior surface of the expandable housing may be maintained such that aseal is created to prevent blood flow between the rim and interiorsurface. Additionally, during the pump stroke, blood is pulled into theexpandable housing. Depending on the variation of pump used, blood maybe pulled into the expandable housing from the left ventricle or theaorta. The pump stroke may generally push blood out of the expandablehousing into a portion of the aorta, for example, the ascending aorta orthe descending aorta. During the pumping cycle, the flaps in the flowcontrol layer of the valve cone close during the pump stroke and openduring the fill stroke. When a flexible diaphragm is employed, it may becollapsed to the collapsed configuration during the fill stroke andextended to the extended configuration during the pump stroke.

The pump may be advanced and positioned in various parts of thecirculatory system of the patient. For example, the expandable housingof the pump may be advanced through the aortic valve and into the leftventricle of the patient. When the pump further comprises a cannula, andthe cannula may be advanced through the aortic valve and into the leftventricle of the patient. Non-limiting examples of target locations forthe expandable housing include the aortic arch, the descending aorta,the thoracic aorta, and the abdominal aorta.

As previously described, the expandable housing may comprise a pluralityof openings or perforations, and a skirt coupled to the expandablehousing. In this instance, blood exiting the openings may be directed ina retrograde direction toward the heart of the patient during the pumpstroke by the skirt. The length of the skirt may be adjusted to achievea predetermined amount of retrograde blood flow toward the heart of thepatient. The number of openings may also be adjusted to achieve apredetermined amount of retrograde blood flow toward the heart of thepatient. Alternatively, the diameter of the openings may be adjusted toachieve a predetermined amount of retrograde blood flow toward the heartof the patient. Adjustment of any one or combination of the foregoingfeatures may be utilized so that about 60% of the blood from the pumpstroke flows in a retrograde direction toward the heart of the patientabout 50% of the blood from the pump stroke flows in a retrogradedirection toward the heart of the patient, or about 40% of the bloodfrom the pump stroke flows in a retrograde direction toward the heart ofthe patient.

When the pump is disposed external to the patient, the method forpumping blood may include accessing the circulatory system of a patientwith a coaxial catheter and coupling the coaxial catheter to the housingof the pump. The housing may comprise an interior surface. A flexiblediaphragm contained within the housing may comprise a diaphragm body anda rim, where the flexible diaphragm has an extended configuration and acollapsed configuration. Alternatively, a valve cone may be disposedwithin the housing to linearly reciprocate therein. The external pumpmay be disposed within, or attached to, a console comprising a userinterface.

Access to the circulatory system may be obtained from any suitableartery or vein, for example, the femoral artery, the subclavian artery,the carotid artery, or the jugular vein. Once access is obtained, thecoaxial catheter may be advanced to a target location in the circulatorysystem and a valve member, for example, a valve cone or flexiblediaphragm, linearly reciprocated within the expandable housing togenerate a fill stroke and a pump stroke of a pumping cycle. During thepump stroke, contact between the rim of the valve cone or the flexiblediaphragm and the interior surface of the expandable housing may bemaintained to create a seal therebetween and prevent blood from flowingaround the flexible diaphragm. The seal may help generate and maintainthe force of the pump stroke as well as minimize red blood cell damagethat may occur with blood flowing between a space existing between therim and the interior surface. The methods described herein may includeadvancing coaxial catheter to various target locations in a patient. Forexample, the target location for the inflow lumen may a left ventricleof the patient, or the target location for the outflow lumen may beabove an aortic valve of the patient.

The coaxial catheter may comprise an inflow lumen and an outflow lumen.The inflow lumen may receive blood from the left ventricle and theoutflow lumen may return blood to the ascending aorta. In general, thepump stroke may pull blood into the housing through the inflow lumen aswell as push blood out of the housing and through the outflow lumen.During the fill stroke, the flexible diaphragm may be collapsed to thecollapsed configuration. Correspondingly, the flexible diaphragm may beextended to the extended configuration during the pump stroke. When avalve cone is used, the plurality of flaps in the flow control layer maybe open during the fill stroke and closed during the pump stroke. A meshlayer may be provided with the flow control layer to support the flapsand prevent them from opening during the pump stroke.

Other methods for pumping blood may include advancing a pump to a targetlocation within the aorta of a patient, such as the thoracic aorta orthe abdominal aorta, where the pump has a fill stroke and a pump stroke;pulling a fill volume of blood into the pump during the pump stroke; andpushing an exit volume of blood out of the pump during the pump stroke,where the exit volume comprises a first portion of blood and a secondportion of blood. The fill stroke may pull blood from the left ventricleof the patient. Additionally, the first portion of blood may be pumpedin a retrograde direction toward the head of the patient, and the secondportion of blood may be pumped in an anterograde direction. The secondportion of blood may be about 60% of the exit volume, about 50% of theexit volume, or about 40% of the exit volume.

In some methods, an expandable housing having a cannula extending from aproximal end of the housing is advanced within a selected artery andpositioned at a target location, such as the patient's aorta and leftventricle. The selected artery may be the femoral artery. Once at thetarget location, a sheath surrounding the expandable housing may bewithdrawn, thereby allowing the expandable housing to expand to itspumping configuration. An actuator may then be advanced into the housingand a linear motor drive activated to induce reciprocating motion of avalve member (e.g., a valve cone or a flexible diaphragm) coupledthereto within the expandable housing in forward and rearwarddirections. During the reciprocating movement, forward movements mayinduce blood flow into the housing and rearward movements may exert apumping force against blood within the housing. The result is a linearpulsatile pumping action that may be extremely efficient, and which maybe compatible with the pulsatile behavior of the human heart. Thecharacteristics of the reciprocating movement of the pumps describedherein may be independently varied to provide optimized forward strokes,rearward strokes, and movement profiles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a perspective view of an exemplary pump and linear motordrive.

FIG. 2 depicts the pump of FIG. 1 being advanced within the aorta to aleft ventricle of the heart.

FIG. 3 illustrates the movement of blood resulting from a pumping strokeof the pump of FIG. 2.

FIG. 4 illustrates the filling stroke of the pump of FIG. 2.

FIG. 5 depicts an enlarged cross-sectional view of the pump of FIG. 1prior to deployment in a heart.

FIG. 6 depicts an enlarged cross-sectional view of the pump of FIG. 1 atan intermediate point during its configuration for pumping operation.

FIG. 7 depicts an enlarged cross-sectional view of the pump of FIG. 1 atthe completion of its configuration for pumping operation.

FIG. 8 depicts an enlarged cross-sectional view of the pump of FIG. 1during a filling stroke portion of its pumping operation.

FIG. 9 depicts an enlarged cross-sectional view of the pump of FIG. 1during a pumping stroke portion of its pumping operation.

FIGS. 10A-10C depict side views of an exemplary housing comprising ascaffold and blocking layer. The scaffold is shown in FIG. 10A and theblocking layer in FIG. 10B. In FIG. 10C, the scaffold is shown coupledto the blocking layer.

FIG. 11 depicts a perspective view of an exemplary pump including thehousing of FIG. 10C and a flexible diaphragm supported by a plurality oftines.

FIGS. 12A and 12B depict an enlarged view of a flexible diaphragmaccording to one variation. FIG. 12A shows a top view of flexiblediaphragm and FIG. 12B shows a side, cross-sectional view of thediaphragm in FIG. 12A taken along line A-A.

FIGS. 13A-13C depict enlarged views of a plurality of tines according toone variation. FIG. 13A shows a side view of the plurality of tines;FIG. 13B shows a side, cross-sectional view of the tines of FIG. 13Ataken along line A-A; and FIG. 13C shows a front view of the tines ofFIG. 13A, illustrating their spacing from one another.

FIGS. 14A-14C depict enlarged views of another exemplary design for theplurality of tines. FIG. 14A shows a side view of the plurality oftines; FIG. 14B shows a side, cross-sectional view of the tines of FIG.14A taken along line A-A; and FIG. 14C shows a front view of the tinesof FIG. 14A, illustrating their spacing from one another.

FIG. 15 depicts a perspective view of another exemplary pump including aconical shaped flexible diaphragm.

FIGS. 16A-16C depicts enlarged views of the conical shaped flexiblediaphragm of FIG. 15. FIG. 16A shows a top view of the diaphragm of FIG.15; FIG. 16B shows a side view of the diaphragm of FIG. 16A, and FIG.16C shows a side, cross-sectional view of the diaphragm of FIG. 16B.

FIG. 17 illustrates seal formation between an exemplary conical shapedflexible diaphragm and an interior surface of a housing.

FIGS. 18A and 18B depict a pump according to another variation, wherethe housing lacks a cannula extending therefrom. FIG. 18A shows the pumppositioned in the descending thoracic portion of the aorta. FIG. 18Bshows the pump positioned in the descending abdominal portion of theaorta.

FIG. 19 depicts an exemplary pump comprising a housing that includes aplurality of openings and a skirt coupled to the housing.

FIG. 20 depicts an enlarged view of the housing of FIG. 19 with a cutout to show how the skirt and plurality of openings work with theflexible diaphragm to generate retrograde blood flow.

FIG. 21 illustrates how blood flows during a pumping cycle includingretrograde and anterograde flow.

FIGS. 22A-22C depict a pump according to yet another variation, coupledto a linear motor drive external to the patient. FIG. 22A shows the pumpwithin the patient and coupled to the linear motor drive within anexternal console; FIG. 22B shows a close-up view of the housing of thepump within the patient; and FIG. 22C shows a close-up view of thedistal end of the cannula within the left ventricle.

FIGS. 23A-23C depict an exemplary external pump disposed within abedside console, coupled to the patient via a coaxial catheter. FIG. 23Ashows the coaxial catheter within the patient and coupled to linearmotor drive within a bedside console; FIG. 23B shows a close-up view ofthe inflow and outflow lumens of the coaxial catheter; and FIG. 23Cshows a close-up view of the inlet and outlet of the coaxial catheter.

FIGS. 24A-24C depict exemplary locations for pressure sensor attachmentto the pump. FIG. 24A shows a perspective view of the pump and pressuresensors; FIG. 24B shows an enlarged view of two pressure sensors at theoutlet of the pump; and FIG. 24C shows an enlarged view of two pressuresensors at the inlet of the pump.

FIGS. 25A-25C depict an exemplary valve member including an expandableframe, a mesh cone, and a flow control cone. FIG. 25A shows the meshcone and the flow control cone coupled to the expandable frame; FIG. 25Bshows an assembly view of the expandable frame, mesh cone, and flowcontrol cone; and FIG. 25C shows the mesh cone and flow control conestitched to the expandable frame at multiple attachment points.

FIGS. 26A-26C depict the expandable frame shown in FIGS. 25A and 25B.FIG. 26A shows a perspective view of the expandable frame; FIG. 26Bshows a side view of the expandable frame; and FIG. 26C shows a top viewof the expandable frame.

FIGS. 27A and 27B depict the mesh cone of FIGS. 25A to 25C. FIG. 27Ashows a circular piece of mesh including a free edge, which may berolled into the cone shape shown in FIG. 27B.

FIGS. 28A-28C depict the flow control cone of FIGS. 25A to 25C. FIG. 28Ashows a circular piece of material including a plurality of flaps and afree edge; FIG. 28B shows a rim running circumferentially about theperiphery of the material; and FIG. 28C shows the circular piece ofmaterial rolled into a cone shape.

DETAILED DESCRIPTION

Described herein are pumps for assisting blood circulation. Instead of arotary impeller, the pumps may include a linearly reciprocating memberto move blood, which may help avoid the shear forces that cause redblood cell damage, and which pumps blood in a pulsatile fashion,mimicking the natural pumping cycle of the heart. The pumps may create apressure wave or back pulse during the fill stroke to assist with theoperation of the associated heart and may eliminate the collapse ofblood vessels. Furthermore, the pumps may be able to provide adequateblood flow at operational speeds between 50 and 500 cycles per minute,which provides very slow movement compared to rotary impellers, andwhich may prevent red blood cell hemolysis. With slower pump speeds,less heat may be generated than rotary impellers, avoiding the need toinclude cooling apparatuses.

The linearly reciprocating member may include a valve member constructedsuch that a seal is created between it and the housing during a pumpstroke of the pumping cycle, thereby generating the blood pressureneeded to move blood peripherally. The pump stroke and length of thelinearly reciprocating member, as well as the stroke speed, may beindependently adjustable. Blood pressure and blood flow rate may becontrolled by stroke length and speed adjustments. Furthermore,adjustable front and back stroke speed ramping may avoid a jolt withinthe pressure characteristics of the circulatory system. The pumps may beplaced in various parts of the circulatory system of a patient, such asthe left ventricle, the right ventricle, and the aorta. However, in someinstances it may be useful to have the pump external to the patient.

Pumps

The pumps for assisting blood circulation described herein may include ahousing and a linearly reciprocating member that comprises a valvemember, for example, a flexible diaphragm or valve cone, disposed withinthe housing. The housing may be expandable and include an interiorsurface, an expanded configuration, and a collapsed configuration. Asheath, which may be concentrically disposed about the housing, maymaintain the housing in the collapsed configuration during advancementto a target location. Upon reaching the target location, the sheath maybe retracted to allow expansion of the housing to the expandedconfiguration. Additionally, the flexible diaphragm may have an extendedconfiguration and a collapsed configuration, and may include a diaphragmbody and a rim. Likewise, the valve cone may have an expandedconfiguration and a collapsed configuration, and may include a layerhaving a plurality of flaps that allow blood flow into the housingduring the fill stroke but prevents blood flow through the valve coneduring the pump stroke. A bearing within the expandable housing may alsobe provided to contain movement of the flexible diaphragm or valve conewithin the housing.

The pumps may also include an actuator coupled to the flexible diaphragmor valve cone via a support element, which may be configured to linearlyreciprocate the flexible diaphragm or valve cone within the housing togenerate a fill stroke and a pump stroke of a pumping cycle. The rim ofthe flexible diaphragm or the valve cone may be configured to maintaincontact with the interior surface of the housing during the pump stroke.However, the support elements may generally be sized and/or shaped sothat they do not contact the inside surface of the housing while theylinearly reciprocate within the housing. The pumps may be driven by anexternal linear motor drive and linear motor controller, which may besituated at the proximal end of a catheter external to the patient. Thelinear motor drive may be operatively coupled to the pump by a cable orother actuator. Furthermore, the pumps may be powered by AC or DCsources.

Housing

In general, the housing of the pump comprises a body, a proximal end,and a distal end. Additionally, the housing may be expandable andinclude an expanded configuration and a collapsed configuration, aspreviously stated. The housing may define a chamber for collecting andholding blood until moved out by a pump stroke, and may comprise asupport or scaffold and a covering. The housing may be advanced to atarget location within the circulatory system of a patient in thecollapsed configuration. Upon reaching the target location, the housingmay then be expanded to the expanded configuration to provide a chamberfor collection of the blood to be pumped. The housing may have adiameter ranging from about 12 mm to about 20 mm in its expandedconfiguration, including all sub-ranges therein. For example, thehousing may have a diameter of about 12 mm, about 13 mm, about 14 mm,about 15 mm, about 16 mm, about 17 mm, about 18 mm, about 19 mm, orabout 20 mm in its expanded configuration. The diameter may be selectedbased on such factors as the location at which the housing will reside,the age of the patient, and whether other features, e.g., a cannula,coaxial catheter, skirt, etc., are utilized with the housing.

The support or scaffold may also include a proximal end and a distalend. The scaffold may be formed from braided, woven, and/or coiledfilaments, and may be made from various materials. For example, scaffoldmaterials may include biocompatible polymers and metals comprisingstainless steel, titanium, or alloys thereof. For example, the scaffoldmay comprise a nickel-titanium alloy (Nitinol). With respect to theproximal and distal ends of the scaffold, they may be tapered, blunt, orstraight. Furthermore, the distal end of the scaffold may include aninlet for blood flow during the pump stroke. The proximal end of thescaffold may include an outlet for blood flow during the pump stroke. Inone variation, the scaffold may be a self-expanding stent.

The housing may further comprise a covering or layer configured to blockthe flow of blood. The covering or layer may be provided on the entirescaffold or on a section or portion of the scaffold. In one variation,the covering or layer may comprise a polymer, and may thus form apolymer layer. The polymer layer may be overmolded on the scaffold suchthat scaffold is embedded within the polymer layer. In some variations,the scaffold may be positioned within the center of the polymer layer,while in other variations, the scaffold may be positioned toward aninner or outer edge of the polymer layer. Embedding or otherwiseentirely covering the scaffold with the polymer layer may provide theexpandable housing with a smooth interior surface. The polymer layer maycomprise an elastomeric polymer such as, but not limited to, silicone,polyester, polyurethane, or a combination thereof. Alternatively, thecovering or layer may comprise a fabric, and may thus form a fabriclayer. In these variations, the expandable housing may include a fabriclayer coupled to the scaffold, usually to an interior surface of thescaffold. The fabric layer may be coupled to the scaffold by anysuitable means, such as, for example stitching the fabric layer to thescaffold at one or more points (e.g., a plurality). The stitch pointsmay be specifically selected such that the fabric layer forms a smoothsurface (e.g., on the interior of the housing) so as not to disrupt theinterface between the flexible diaphragm and the housing. In othervariations, the fabric layer may be coupled to the scaffold using anadhesive such as an acrylic adhesive, a cyanoacrylate adhesive, or asilicone adhesive. Non-limiting examples of materials that may be usedas the fabric layer include a woven material such as buckram or amaterial woven from polyester fibers. A film or sheet of non-wovenmaterial such as Mylar® plastic film may also be used.

In some instances, the housing of the pump (e.g., the covering or layer)may include a plurality of openings or perforations. The number ofopenings utilized may range from about 2 to about 25, including allvalues and sub-ranges therein. For example, the expandable housing mayinclude 2 openings, 3 openings, 4 openings, 5 openings, 6 openings, 7openings, 8 openings, 9 openings, 10 openings, 11 openings, 12 openings,13 openings, 14 openings, 15 openings, 16 openings, 17 openings, 18openings, 19 openings, 20 openings, 21 openings, 22 openings, 23openings, 24 openings, or 25 openings. The openings may be equally orunequally spaced on a portion of the housing, and/or arranged in apattern on a portion of the housing. Additionally, the plurality ofopenings may have a diameter ranging from about 0.10 mm to about 6.50mm, including all values and sub-ranges therein. For example, thediameter may be about 0.10 mm, about 0.5 mm, about 1.0 mm, about 1.5 mm,about 2.0 mm, about 2.5 mm, about 3.0 mm, about 3.5 mm, about 4.0 mm,about 4.5 mm, about 5.0 mm, about 5.5 mm, about 6.0 mm, or about 6.5 mm.The plurality of openings in the expandable housing may have the samediameter or different diameters. Furthermore, the plurality of openingsmay have any suitable shape, for example, circular, ovoid, or slot-like.In variations comprising slots, the slots may be linear, v-shaped, orarcuate in shape. In one variation, the housing includes four openingsevenly spaced about the housing.

When the housing includes openings or perforations, a skirt may becoupled to the expandable housing in a manner that covers, surrounds, orotherwise overlies the plurality of openings to assist in generatingretrograde blood flow directed toward the patient's head during the pumpstroke of a pumping cycle. The retrograde blood flow may help provideadequate perfusion of arteries branching from the aortic arch, forexample, the carotid arteries and subclavian arteries. The ability tomaintain adequate perfusion of the subclavian artery may prevent flowreversal from the vertebrobasilar artery to the subclavian artery, aphenomenon known as “subclavian steal.” The combination of the number ofopenings and opening diameter may provide an amount of open surface areaon the housing for retrograde blood flow. Additionally, the skirt may beconfigured to adjust the amount of open surface area for retrograde flowby adjusting the number of patent (open) and closed openings. Ingeneral, a larger amount of open surface area may provide moreretrograde blood flow toward the head and heart of the patient, and asmaller amount of open surface area may provide a greater amount ofanterograde blood flow to the body. In some variations, a mechanism thatlifts, opens, or flares the skirt off the external surface of thehousing may be provided. For example, a tether may be coupled to theskirt, e.g., around the external surface of the skirt, and configured toopen and close the skirt against the housing similar to how a noose canbe tightened and loosened. The amount of opening or closing may beadjusted using a rotatable dial disposed, e.g., on a console external tothe patient.

The skirt may have any suitable shape that directs blood back toward thehead and heart (e.g., cylindrical or frustoconical), and may be coupledto the housing in various ways. In one variation, the skirt may be aseparate component from the housing and may be attached to the housingby any suitable means, such as, for example, friction fit or using anadhesive. In another variation, the skirt may be integral with thehousing (e.g., the two may be formed integrally, such as, by molding thetwo as a single component). The skirt may be made from the samematerials as the housing. For example, the skirt may comprise a meshmade from stainless steel, titanium, or alloys thereof (e.g., Nitinol),and a polymer or fabric layer. The length of the skirt may also vary,and range from about 0.32 cm (0.125 inch) to about 1.90 cm (0.750 inch).

Cannula

In some variations, the pumps may include a cannula comprising anelongate body, a proximal end, a distal end, and a lumen runningtherethrough. The cannula may be coupled to the housing as a separatecomponent, or be integrally formed as an extension thereof. Depending onthe placement of the housing, the cannula may be coupled or extend fromthe proximal or distal end of the housing. For example, when the housingresides within the left ventricle, a cannula may extend from theproximal end of the housing such that it traverses the aortic valve andextends into the ascending aorta. In other variations, the pumps mayinclude a cannula extending from the distal end of the housing. Forexample, when the housing resides in the aorta, a cannula may extendfrom the distal end of the housing such that it traverses the aorticvalve to extend into the left ventricle. In further variations, thehousing may not have a cannula extending therefrom. In these instances,the housing may reside within any portion of the aorta, for example, thethoracic aorta or the abdominal aorta.

Cannulas of various lengths may be used. For example, short, medium, orlong cannulas may be used. When a short cannula is employed, the lengthof the cannula may range from about 2.5 cm to about 5.0 cm, includingall values and sub-ranges therein. For example, the length of the shortcannula may be about 2.5 cm, about 3.0 cm, about 3.5 cm, about 4.0 cm,about 4.5 cm, or about 5.0 cm. When a medium length cannula is used, thelength of the cannula may range from about 25 cm to about 30 cm,including all values and sub-ranges therein. For example, the length ofthe medium cannula may be about 25 cm, about 26 cm, about 27 cm, about28 cm, about 29 cm, or about 30 cm. When a long cannula is used, thelength of the cannula may range from 35 cm to about 40 cm, including allvalues and sub-ranges therein. For example, the long cannula may beabout 35 cm, about 36 cm, about 37 cm, about 38 cm, about 39 cm, orabout 40 cm. In some variations, a pump may be provided with each of ashort, a medium, and a long cannula and a user may select theappropriate cannula based on desired use of the pump. It should beappreciated, that in some instances, other cannula lengths may also beused.

Coaxial Catheter

As mentioned above, in some variations the pump may be disposed externalto the body, for example, within a console at the patient's bedside. Inthese variations, the pump may further comprise a coaxial catheter. Afirst end of the coaxial catheter may be coupled to the housing of thepump via a connector or adapter and the opposite (second) end of thecoaxial catheter may be inserted into the patient such that blood flowsbetween the patient and the housing. The coaxial catheter may have anoutside diameter between about 1° F. and about 18 F, including allvalues and sub-ranges therein. For example, the outside diameter of thecoaxial catheter may be about 10 F, about 11 F, about 12 F, about 13 F,about 14 F, about 15 F, about 16 F, about 17 F, or about 18 F. Thecoaxial catheter may include an inflow lumen and an outflow lumen. Insome variations, the outflow lumen may be concentrically disposed aboutthe inflow lumen. In other variations, the inflow and outflow lumens mayextend parallel to one another within the coaxial catheter. The inflowlumen may generally have an internal diameter between about 7 F andabout 14 F.

The inflow and/or outflow lumens of the coaxial catheter may be flushed,e.g., with sterile saline or heparinized saline. Flushing may beperformed at any time, but is generally performed prior to use of thecoaxial catheter. The fluid for flushing the coaxial catheter may beintroduced into one or more of the catheter lumens by various types ofconnectors, for example, Y connectors or two or three way connectors.Other types of catheter connectors and fittings may also be used.Flushing around the coaxial catheter site may also be performed aroundthe site of insertion into the body.

Valve Cone

The linearly reciprocating member of the pumps described herein mayinclude a valve member such as a valve cone. The valve cone may bedisposed within the expandable housing and may include a plurality ofmaterial layers coupled to a support member. The support member may bean expandable frame. However, in some variations, a single layer ofmaterial may be coupled to the support member. As previously mentioned,the valve cone may have an inlet side that faces the inlet of theexpandable housing, and an outlet side that faces the outlet of theexpandable housing. The plurality of material layers may include meshlayers, flow control layers, or a combination thereof. Any number ofmaterial layers may be used, as long as at least one flow control layeris included. The flow control layer generally includes a plurality offlaps that open when blood is pulled into the expandable housing duringthe fill stroke, and which close when blood is moved out of theexpandable housing during the pump stroke. The mesh layer may bedisposed between the flow control layer and the expandable frame andused to support the flow control layer such that when pressure againstthe flaps is applied during the pump stroke, the flaps are not pushed orbent through the openings in the expandable frame. Thus, the mesh layermay help maintain the flaps in the closed configuration during the pumpstroke when blood is moved out of the housing via the housing outlet.However, during the fill stroke, the mesh layer permits blood to flowfrom the housing inlet through the holes in the mesh and then throughthe flaps, transitioning them to their open configuration so that bloodmay move to the outlet side of the valve cone.

Woven fabrics or elastomeric polymers may be used to form the meshlayer. Exemplary elastomeric polymers include without limitation, asilicone, a polyester, a polyurethane, or a combination thereof. Thethickness of the mesh layer may range from about 0.03 mm to about 0.05mm, including all values and sub-ranges therein. The size and shape ofthe mesh openings may also vary and may depend on the size and shape ofthe flaps in the flow control layer given their supportive function, asdescribed above. With respect to shape, the mesh openings may becircular, triangular, square, rectangular, or diamond shaped, etc.

The material layers may be coupled to the expandable frame in anysuitable manner, for example, by stitching, suturing, or embroidering,by use of an adhesive, by heat sealing, or by welding. The materiallayers may be coupled to the expandable frame at a plurality ofattachment points on the frame. The expandable frame may have anexpanded configuration and a collapsed configuration, and comprisestainless steel, nickel, titanium, or alloys thereof (e.g., nitinol). Inone variation, the expandable frame is made from a laser cut nitinoltube. The expandable frame may have a first end that couples to theactuator of the pump, and a shaped second end that couples to thematerial layers of the valve cone. In general, the shape of the valvecone corresponds to the shape of the expandable frame. Although theexpandable frame typically has a conical shape, any shape capable ofbeing collapsed to permit advancement through the cannula may be used.When the expandable frame is conically shaped, the plurality of materiallayers (e.g., the mesh and flow control layers) may also be conicallyshaped.

The flow control layer of the valve cone may also be formed from variouspolymers, for example, an elastomeric polymer as stated above, or fromMylar® plastic film. The flow control layer may include a plurality offlaps having an open configuration and a closed configuration. Ingeneral, the plurality of flaps are in the open configuration during thefill stroke, and in the closed configuration during the pump stroke. Theflow control layer may be cut to create a plurality of flaps, which maybe of any suitable size and shape that allows blood to flow into thehousing during the fill stroke. For example, the flaps may have asemi-circular shape, an arc shape, a circular shape, a triangular shape,a diamond shape, a square shape, or a rectangular shape. Any suitablenumber of flaps in the flow control layer may also be employed. Thenumber of flaps may range from 2 to 20. For example, 2 flaps, 3 flaps, 4flaps, 5 flaps, 6 flaps, seven flaps, 8 flaps, 9 flaps, 10 flaps, 11flaps, 12 flaps, 13 flaps, 14 flaps, 15 flaps, 16 flaps, 17 flaps, 18flaps, 19 flaps, or 20 flaps may be included. In one variation, a flowcontrol layer including 15 flaps may be useful. The valve cone may beconfigured such that a greater number of flaps are included when theyare smaller in size, and a smaller number of flaps are included whenthey larger in size. When the flaps are semi-circular in shape, they mayhave a radius ranging from about 0.50 mm to about 3.0 mm, including allvalues and sub-ranges therein.

When the cone valve is conically shaped, the flow control layer isgenerally also conically shaped. Here the material of the flow controllayer may first be provided as a circle with center cut out and a slitextending from the cut out to the periphery of the circle (e.g., see28A). The slit provides a free edge so that the layer may later berolled to form a cone shape. Next, the flaps may be formed by lasercutting or stamping the flap shapes into the flow control layer. Theflaps may have any suitable size and shape, as previously stated. In onevariation, a rim is then created at the periphery of the circle byrolling the edge of the flow control layer upon itself to createthickness at the periphery and stitching, heat sealing, gluing, etc.,the rolled edge to maintain the thickness in that area. In anothervariation, the edge may be rolled over an O-ring to form the rim. In afurther variation, the rim is a separate component from the flow controllayer, and includes an O-ring that is stitched, heat sealed, glued,bonded, etc., to the edge of the flow control layer. After the rim isformed, a free edge of the circular flow control layer is rolled toshape it into a cone. The rim may help create a seal between the rim ofthe flow control cone and the interior surface of the housing during thepump stroke. A conically shaped mesh layer may be formed by the sameprocess except that a rim need not be included.

In addition to a rim, the flow control layer may include a body. Thebody and the rim may be made from the same material or from differentmaterials. Additionally, the body and the rim may be separate componentsor integrally formed with one another. When provided as separatecomponents, the body may be formed from an elastomeric polymer or fromMylar® plastic film, and the rim may be an O-ring. The peripheral edgeof the flow control layer may be rolled over the O-ring to form the rim.The thickness of the rim may be greater than the thickness of the body.The body may have a thickness ranging from about 0.03 mm to about 0.05mm, including all values and sub-ranges therein. The rim may have athickness ranging from about 0.20 mm to about 1.5 mm, including allvalues and sub-ranges therein. For example, the rim may have a thicknessor about 0.20 mm, about 0.30 mm, about 0.40 mm, about 0.50 mm, about0.60 mm, about 0.70 mm, about 0.80 mm, about 0.90 mm, about 1.0 mm,about 1.1 mm, about 1.2 mm, about 1.3 mm, about 1.4 mm, or about 1.5 mm.

Flexible Diaphragm

In some variations, the linearly reciprocating member of the pumpsdescribed herein may include a flexible diaphragm as the valve member.The flexible diaphragm may be contained within the housing. The flexiblediaphragm may have a collapsed configuration and an extendedconfiguration, and may linearly reciprocate within the housing. In thecollapsed configuration, the flexible diaphragm may have a smallerdiameter than when in the extended configuration to allow advancementthrough the vasculature. Once at the target location in the patient, theflexible diaphragm may be transformed to its extended configuration tomove blood from an inlet of the housing, through a body of the housing,to and through an outlet of the housing, and create the pressure neededfor pumping blood. The flexible diaphragm may be coupled to a supportmember, which in turn is coupled to an actuator that linearlyreciprocates the flexible diaphragm within the housing. The supportmember may be an expandable frame that is conically shaped or a tinesupport, as further described below. Coupling to the expandable framemay be accomplished in any suitable manner, for example, by stitching,suturing, or embroidering, by use of an adhesive, by heat sealing, or bywelding. The flexible diaphragm may include a diaphragm body and a rim.In some variations, the flexible diaphragm may comprise an elastomericpolymer. Non-limiting examples of elastomeric polymers include but arenot limited to: silicone, polyester, polyurethane elastomers, or acombination thereof. The body and rim of the flexible diaphragm maycomprise the same material or different materials. In some instances,the diaphragm body and rim are integrally formed.

The material and/or thickness of the diaphragm body and rim may beselected so that the flexible diaphragm is able to bend and allow bloodto flow around it during a fill stroke, but resilient enough to preventthe flexible diaphragm from everting or folding upon itself during apump stroke. Furthermore, the material and/or thickness of the flexiblediaphragm may be sufficiently rigid so that the pressure needed toeffect a pump stroke is generated as well as to prevent stretching ofthe diaphragm body. In one variation, the flexible diaphragm maymaintain its shape during the pumping cycle by including a rim thickerthan the diaphragm body.

In some variations, thicknesses of the diaphragm body may range fromabout 0.03 mm to about 0.3 mm, including all values and sub-rangestherein. For example, diaphragm thickness may be about 0.03 mm, about0.04 mm, about 0.05 mm, about 0.06 mm, about 0.07 mm, about 0.08 mm,about 0.09 mm, about 0.10 mm, about 0.20 mm, or about 0.30 mm. Withrespect to the rim of the diaphragm, its thickness may range from about0.20 mm to about 1.5 mm, including all values and sub-ranges therein.For example, the rim thickness may be about 0.20 mm, about 0.30 mm,about 0.40 mm, about 0.50 mm, about 0.60 mm, about 0.70 mm, about 0.80mm, about 0.90 mm, about 1.0 mm, about 1.1 mm, about 1.2 mm, about 1.3mm, about 1.4 mm, or about 1.5 mm. In some variations, the rim thicknessmay range from about 0.5 mm to about 1.0 mm, including all values andsub-ranges therein. The thickness of the rim may be greater than thethickness of the diaphragm body, which may help the flexible diaphragmmaintain its shape during the pumping cycle, as mentioned above. Agreater rim thickness may also aid in creating a seal between the rimand interior surface of the housing during the pump stroke. However, insome variations, the rim and body may have equal thicknesses. The ratioof the thickness between the diaphragm body and rim may range from about1:5 about 1:20. The rim of the flexible diaphragm may have a widthranging from about 1.0 mm to about 2.0 mm, including all values andsub-ranges therein. In one variation, the diaphragm body may have athickness of about 0.05 mm and the rim may have a thickness of about0.25 mm.

Furthermore, the flexible diaphragm may have any suitable shape orgeometry capable of creating a seal between the rim of the diaphragm andthe interior surface of the housing during the pump stroke. For example,the flexible diaphragm may have a conical, frustoconical, orhemispherical shape when in the extended configuration. The flexiblediaphragm may also comprise a plurality of ribs that may help providemore rigidity to the flexible diaphragm body. In one variation, theflexible diaphragm has a conical shape and a plurality of ribs that aidin maintaining the conical shape during a pump stroke. The plurality ofribs may be integrally formed with the diaphragm body, or they may beseparate components coupled to the diaphragm body by, e.g., use of anadhesive, welding, etc. In some variations, the plurality of ribs mayradiate from a center portion of the diaphragm body to the rim. Theplurality of ribs may have a rib angle between a longitudinal axis of arib of the plurality of ribs and an axis perpendicular to the actuatorthat ranges from about 30 degrees to about 60 degrees, including allvalues and sub-ranges therein. For example, the rib angle may be about30 degrees, about 35 degrees, about 40 degrees, about 45 degrees, about50 degrees, about 55 degrees, or about 60 degrees. The plurality of ribsmay be equally spaced from one another. In some variations, theplurality of ribs may have unequal spacing from one another.

Actuator/Controller

The pumps described herein may include an actuator coupled to the valvemember, usually via a support member. The valve member may be a flexiblediaphragm or a valve cone. The actuator may be generally configured tolinearly reciprocate the flexible diaphragm or valve cone within thehousing to generate a fill stroke and a pump stroke of a pumping cycle.Exemplary actuators may include without limitation, a cable, a wire, arod, or other actuator having the flexibility to track over a guidewireand navigate the vasculature, as well as the stiffness needed toreciprocate the flexible diaphragm during the pump and fill strokes. Thelinear reciprocating movement of the actuator may be generated by alinear motor drive and linear motor controller. Although the linearmotor is usually situated external to the patient, in some variations,the linear motor may be implanted within the patient, e.g., in asubcutaneous pocket, or provided as part of the pump placed within theheart or vasculature of the patient.

The linear motor controller may regulate various parameters of thepumping cycle. For example, the linear motor controller may regulate thespeed of linear reciprocation of the actuator and flexible diaphragm,and the length of the pump and fill strokes. In some variations, theadjustment or control of pump parameters may be accomplished manually,e.g., by one or more control features provided on an external console.In other variations, pump parameters may be adjusted automatically,e.g., using a closed loop system. The closed loop system may comprise aprocessor and instructions stored in memory of the processor. Duringoperation of the pump, the processor may store and/or process data fromthe pump and/or patient, and may execute instructions from memory toautomatically adjust pump parameters based on data received from one ormore sensors provided with the pump.

Non-limiting examples of sensors for controlling pump parameters includepressure sensors, flow sensors, temperature sensors, heart rate sensors,and heart rhythm sensors. The pressure sensors may be placed in variouspump locations. In some variations, one or more pressure sensors may bemounted in or on a blood flow inlet or inlet/inflow tubing, and one ormore pressure sensors may be mounted in or on a blood flow outlet,outlet/outflow tubing, or skirt of the pump. In other variations, twopressure sensors may be mounted in or on the inlets and outlets forredundancy in case one inlet and/or outlet pressure sensor fails. Infurther variations, one or more pressure sensors may be mounted near ablood flow inlet or inlet/inflow tubing, and one or more pressuresensors may be mounted near a blood flow outlet, outlet/outflow tubing,or skirt of the pump. The pressure sensors may be communicativelycoupled to the controller such that the controller may receivemeasurements from the pressure sensors and may utilize thosemeasurements to modify pump parameters, as stated above. For example, insome variations, the controller may be configured to have predeterminedhigh blood pressure set points, low blood pressure set points and/or apredetermined target blood pressure range. The controller may be furtherconfigured to compare the measurements received from one or more of thepressure sensors to the high blood pressure set points, low bloodpressure set points, and/or the predetermined desired blood pressurerange and to modify one or more pump parameters (e.g., speed ofreciprocation) accordingly. For example, when measurements from thepressure sensors indicate that a patient's measured blood pressure hasdropped below the low set point and/or is below the desired range, thecontroller may increase the speed of the linear reciprocation. Whenmeasurements from the pressure sensors indicate that a patient'smeasured blood pressure has risen above the high blood pressure setpoint and/or is above the desired range, the controller may decrease thespeed of the linear reciprocation to thereby reduce flow and returnblood pressure back below the high set point and/or within the targetrange.

Tines

Some variations of the pumps described herein may also comprise a tinesupport as the support member. The tine support may comprise a base anda plurality of tines configured to support the flexible diaphragm in theextended configuration during the pump stroke. In other variations, asdescribed further below in FIGS. 5-7, the tine support may be coupled tothe flexible diaphragm. The plurality of tines may be flexible and/orresilient, and may have an expanded configuration and a compressedconfiguration. In the compressed configuration, the plurality of tinesmay have a smaller diameter than when in the extended configuration toallow advancement through the vasculature. Once at the target locationin the patient, the plurality of tines may be expanded to a largerdiameter. Furthermore, the plurality of tines may have an expandedconfiguration during the pump stroke of a linear pumping cycle, and acompressed configuration or partially compressed configuration duringthe fill stroke. The plurality of tines may be coupled to the actuator.In one variation, each of the plurality of tines may extend from acommon hub or base to a free end. The hub may be configured to couple tothe actuator. Furthermore, the free ends of the plurality of tines mayradiate or flex outwardly when the plurality of tines move from thecompressed to the expanded configuration.

The number of tines included in the plurality of tines may range fromabout two to about eight. For example, the plurality of tines mayinclude two (2) tines, three (3) tines, four (4) tines, five (5) tines,six (6) tines, seven (7) tines, or eight (8) tines. In one variation,the plurality of tines includes six (6) tines. The plurality of tinesmay be equally spaced or unequally spaced from one another. With respectto materials, the plurality of tines may be made from a metal such asstainless steel, titanium, or alloys thereof, or a biocompatible polymersuch as a fluoropolymer, a polyamide, polyetheretherketone (PEEK), apolyimide, a polyolefin, a polyurethane, or combinations thereof.

In one variation, the plurality of tines may comprise metal strips. Themetal strips may extend from a common base at one end. At the other end,each tine of the plurality of tines has a free end. The free ends may beattached to a barrel, e.g., a short cylinder, by welding, soldering, orgluing. The barrels may provide further supportive area for the flexiblediaphragm to rest against during a pump stroke to help prevent movementof the flexible diaphragm between the tines during the pump stroke. Inone variation, the length of each barrel is about 1.0 mm. The tines maybe made from a metal cylinder that is laser cut to form the strips.

Instead of strips, the plurality of tines may comprise a plurality offlexible first wires. Any suitable number of first wires may beemployed. For example, four (4) wires, six (6) wires, eight (8) wires,ten (10) wires, or 12 (twelve) wires may be used. A plurality of holescorresponding to the number of first wires may be drilled into a base sothat one end of the wires may be inserted into the holes. At the otherend of the wires (free ends), a barrel may be attached in the samemanner described above. The barrels may include a central hole throughwhich a second wire is threaded. After threading through all thebarrels, the ends of the second wire may be joined by soldering,welding, gluing, and the like. The second wire may be made from variousmaterials, including but not limited to, stainless steel, spring steel(piano wire), or nitinol. In some variations, each tine of the pluralityof tines may be comprised of two wires attached to the same barrel attheir free ends. Thus, when the plurality of tines includes 6 (six)tines, the number of wires would be twelve (12). The second wire mayprovide additional flexible diaphragm support to that provided by thebarrels during a pump stroke so that movement of the flexible diaphragmbetween the tines during the pump stroke is prevented or minimized.

Exemplary Variations

An exemplary pump is shown in FIG. 1. As shown there, pump 10 includesan elongated outer sheath 11 having an interior end 12 supporting abearing 13. An expandable housing 25 (better seen in FIG. 3) is receivedwithin the interior of outer sheath 11 and holds bearing 13 in a fixedattachment. An inner sheath 16 extends through the interior of outersheath 11 from bearing 13. Tine support 15 having a plurality of tines20 for supporting a flexible diaphragm 30 is disposed within innersheath 16 in a collapsed configuration. An actuator (drive cable) 40 iscoupled to tine support 15 by a fixed attachment at one end and extendsthrough the interior of inner sheath 16 to attach to linear motor 19within linear motor drive 18 at its other end.

Referring to FIGS. 5, 6 and 7, another variation of the pump isillustrated. In these figures, pump 100 is substantially identical topump 10 both in structure and function with the difference being foundin the configuration of the expandable housings. In comparison to FIGS.3 and 4, it will be noted that pump 10 utilizes an expandable housing 25having a cannula or an extended portion 28 extending therefrom. Turningto FIG. 5, it will be noted that pump 100 utilizes an expandable housing60 that does not have a cannula or extended portion 28. Apart from thisdifference in structure of the expandable housings, pumps 10 and 100 aresubstantially identical.

More specifically, FIG. 5 sets forth a section view of the pulsatilepump portion (expandable housing and flexible diaphragm) of pump 100.FIG. 5 shows the expandable housing 60 in its collapsed configuration.The expandable housing 60 may be advanced from within an outer sheath 11(shown in FIG. 4). Expandable housing 60 includes an inlet (scaffoldportion) 63 proximate end 62, which in turn supports a bearing 13 in afixed attachment. Expandable housing 60 further includes an outlet(scaffold portion) 64 and a chamber 61 within expandable housing 60. Thechamber 61 may be formed by overmolding a portion of the scaffold ofexpandable housing 60 with a polymer layer or coupling a fabric layer tothe scaffold, as previously described. Pump 100 further includes aninner sheath 16 which extends through outlet 64 and chamber 61 to theinterior end of bearing 13. Tine support 15 is received within innersheath 16 and includes a plurality of tines 20. A drive cable 40 extendsthrough inner sheath 16 and is coupled to tine support 15. A flexiblediaphragm 30 is also coupled to tine support 15.

In the configuration shown in FIG. 5, pump 100 has initiated theexpansion of expandable housing 60 while tine support 15 remainscaptivated within inner sheath 16 in the compressed configuration. Thus,the next step in configuring pump 100 for operation requires withdrawinginner sheath 16 to allow the plurality of tines 20 to expand and assumetheir operational expanded configuration.

FIG. 6 sets forth a section view of the pulsatile pump portion of pump100. As mentioned above, FIG. 6 shows pump 100 at a point intermediatebetween the compacted configuration of FIG. 5 and the operationalconfiguration of FIG. 7. Pump 100 includes an expandable housing 60.Expandable housing 60 includes an inlet 63 proximate end 62, which inturn supports a bearing 13 in a fixed attachment. Expandable housing 60further includes an outlet 64 and a chamber 61. pump 100 furtherincludes an inner sheath 16 which has been withdrawn to a point withinoutlet 64 thereby releasing tines 20 and diaphragm 30 from the captivityof inner sheath 16. Expandable housing 60 further includes a chamber 61and an end 62. Tine support 15 is received within inner sheath 16 andincludes a plurality of tines 20. A drive cable 40 extends through innersheath 16 and outer sheath 11 and is coupled to tine support 15. Aflexible diaphragm 30 is also coupled to tine support 15.

In the configuration shown in FIG. 6, pump 100 has initiated theexpansion of expandable housing 60 and release of tine support 15 frominner sheath 16. Thus, the next step in configuring pump 100 foroperation requires allowing tines 20 of tine support 15 and diaphragm 30to expand and assume their operational configurations.

FIG. 7 sets forth a section view of the pulsatile pump portion of pump100. As mentioned above, FIG. 6 shows pump 100 in its operationalconfiguration. Expandable housing 60 includes an inlet 63 proximate end62, which in turn supports a bearing 13 in a fixed attachment.Expandable housing 60 further includes a mesh portion 64 and a chamber61. Pump 100 further includes an inner sheath 16 which has beenwithdrawn to a point within outlet 64 thereby releasing tines 20 anddiaphragm 30 from the captivity of inner sheath 16. Expandable housing60 further includes a chamber 61 and an end 62. Tine support 15 extendspartially into bearing 13. Tine support 15 includes a plurality of tines20 that have expanded to the position shown. A drive cable 40 extendsthrough inner sheath 16 and outer sheath 11 and is coupled to tinesupport 15. Flexible diaphragm 30 is also coupled to tine support 15 andhas expanded to its full extended configuration overlapping the outerends of tines 20.

In the configuration shown in FIG. 7, pump 100 has completed theexpansion of expandable housing 60 and released tine support 15 frominner sheath 16 allowing tines 20 and diaphragm 30 to assume their fullyextended positions. Thus, pump 100 is fully configured for operation.

In some variations, the pumps for assisting blood circulation include anexpandable housing as illustrated in FIGS. 10A to 10C. Referring to FIG.10A, expandable housing 200 has a cannula 202 extending therefrom. Thecannula 202 may have a smaller diameter than the expandable housing 200,which may be useful when the cannula is to traverse the aortic valve.Expandable housing 200 may comprise a scaffold 204, which, in somevariations, may be an expandable stent. Scaffold 204 may include atapered proximal end 208 and a tapered distal end 210, although, it neednot. The distal end 210 may function as an inlet for blood into theexpandable housing 200 and the proximal end 208 may function as anoutlet for blood exiting the expandable housing 200. In order to blockblood from flowing through the stent openings and provide a smoothsurface upon which the flexible diaphragm can reciprocate, theexpandable housing 200 may comprise a layer 206 coupled to and/orcovering the scaffold (e.g., stent) 204. FIG. 10B depicts a polymerlayer 206 that may be overmolded on or otherwise attached to thescaffold 204. The polymer layer 206 may be overmolded on the scaffold204 such that the scaffold 204 is embedded within or otherwise fullysurrounded by the polymer layer 206. FIG. 10C shows the expandablehousing 200 and cannula 202 with the polymer layer 206 coupled to thescaffold 204.

The expandable housing in FIG. 10C may include a flexible diaphragm,which may be, in some variations, supported by a plurality of tines, asshown in FIG. 11. Referring to FIG. 11, flexible diaphragm 212 may bedisposed within a chamber formed in the body of the expandable housing200. and the flexible diaphragm 212 may have a collapsed configurationand an expanded configuration (as depicted in FIG. 11). Flexiblediaphragm 212 may be coupled to actuator 214 such that linear movementof the actuator 214 results in corresponding linear movement of thediaphragm 212. A plurality of tines 216, which may help support theflexible diaphragm 214 against blood pressure during the pump stroke,are also shown in their expanded configuration. The expandable housing200, flexible diaphragm 212, and/or tines 216 may be configured toself-expand, such that expansion of the expandable housing 200, flexiblediaphragm 212, and tines 216 may be achieved by relative motion betweenthe expandable housing 200 and a flexible outer sheath 218 that may beconstraining the expandable housing 200, flexible diaphragm 212 and/ortines during advancement to the desired position in the body (e.g.,retraction of the outer sheath 218 and/or advancement of expandablehousing 200 relative to outer sheath 218).

In general, the flexible diaphragm contained within the expandablehousing moves blood from an inlet of the housing, through the chamber inthe body of the expandable housing, to and through an outlet of thehousing, and creates the pressure for pumping blood. As shown in FIG.12A, the flexible diaphragm 300 in its extended configuration includes adiaphragm body 302 and a rim 304 about the periphery of the body 302.The body 302 and rim 304 of the flexible diaphragm 300 are integrallyformed. However, in other variations, they may be formed separately andcoupled to one another.

In some variations, the diaphragm body 302 and the rim 304 may havedifferent thicknesses. For example, in some variations, the thickness ofthe rim 304 may be greater than the thickness of the diaphragm body 302,as shown in the cross-section view provided in FIG. 12B. The smallerthickness of the diaphragm body 302 may allow the flexible diaphragm tobe in its collapsed configuration during the fill stroke or a portionthereof, and the extended configuration during the pump stroke of apumping cycle. The greater rim thickness may provide the periphery ofthe diaphragm 300 with greater rigidity relative to the diaphragm body302 and may aid in creating a seal between the rim 304 and interiorsurface of the expandable housing during the pump stroke.

Some variations of the pump may include a tine support comprising a baseand a plurality of tines coupled to the actuator that support theflexible diaphragm in the extended configuration during the pump stroke.For example, as shown in FIGS. 13A to 13C, tine support 401 includes abase 404 and a plurality of tines 400. The plurality of tines 400 maycomprise six (6) pliable metal strips 402 having an expandedconfiguration (as shown in the FIG. 13A) and a compressed configuration(see FIG. 5). The metal strips 402 may have a compressed configurationduring advancement of the expandable housing within the vasculature to atarget location, and may expand radially outward to an expandedconfiguration at the target location. Although shown as having arectangular cross-sectional shape, the plurality of tines 400 may haveany suitable shape or geometry, e.g., circular, square, triangular,ovoid, etc. The metal strips 402 may extend from a common hub or base404 at one end, and may have free ends 406 at the other end. As shown inthe cross-section view of FIG. 13B, the base 404 may include a bore 408configured to couple the plurality tines to an actuator. Although shownas including six (6) metal strips 402, more or less strips may beutilized. The metal strips 402 may be equally spaced from one another,as shown in FIG. 13C. However, in some variations, the metal strips 402may be unequally spaced from one another. Also shown in FIGS. 13A to 13Care barrels 412, which are short cylinders attached to the free ends 406of the metal strips 402. The free ends 406 may be attached to a barrel412 using any suitable means, such as, for example, by welding,soldering, or gluing. The barrels 412 may provide further supportivearea for the flexible diaphragm to rest against during a pump stroke tohelp prevent movement of the flexible diaphragm between the tines duringthe pump stroke.

In some variations, the plurality of tines 500 may comprise a pluralityof flexible first wires 502, as illustrated in FIGS. 14A to 14C.Although each tine of the plurality of tines in the figure is shown toinclude two first wires 502, they may include one wire or more than twowires. A plurality of holes (not shown) corresponding to the number offirst wires 502 may be formed (e.g., drilled) in a base 504 of the tinesupport 501 so that one end of the wires may be inserted into the holes.At the other end of the wires (free ends 506), a barrel 508 is attachedin the same manner described above. More specifically, in FIGS. 14A to14C, pairs of first wires 502 are attached to the same barrel at theirfree ends 506 to form one tine of the plurality of tines. Accordingly,six (6) tines are formed when pairing the twelve (12) first wires. Thebarrels 508 may each include a central hole 510 through which a secondwire 512 may be threaded. After threading through all the barrels 508,the ends of the second wire 512 may be joined by soldering, welding,gluing, and/or the like. The second wire may provide additional flexiblediaphragm support to that provided by the barrels during a pump strokeso that movement of the flexible diaphragm between the tines during thepump stroke may be prevented or minimized. As shown in the cross-sectionview of FIG. 14B, the base 504 may include a bore 514 configured forcoupling to an actuator. The first wires 502 may be equally spaced fromone another, as shown in FIG. 14C. However, the first wires 502 may alsobe configured to be unequally spaced from one another.

Other pump variations may not include a plurality of tines supportingthe flexible diaphragm. For example, as shown in FIG. 15, a flexiblecone shaped diaphragm 600 is disposed within expandable housing 602. Theflexible diaphragm 600 may have a compressed configuration and anextended configuration, and may have a conical shape when in theextended configuration. As shown in FIGS. 16A (end view) and 16B (sideview), the flexible diaphragm 600 may include a diaphragm body 604 and arim 606 about the periphery of the body 602. As depicted FIGS. 16A-16B,the body 604 and rim 606 of the flexible diaphragm 600 may be integrallyformed and may be formed from the same material. However, in othervariations, they may be separate components and/or may comprisedifferent materials.

In some variations, the body 604 and the rib 606 may have the samethickness, while in other variations, the thicknesses of the body 604and the rim 606 may differ. For example, in some instances, it may beadvantageous to utilize a diaphragm with a rim 606 that has a greaterthickness than the body 604. Turning to FIG. 17, shown there is anenlarged cross-sectional view of diaphragm 600 in an extendedconfiguration, coupled to actuator 612 and positioned within the chamberof the body of expandable housing 614. Rim 606 contacts interior surface612 of the expandable housing 614 such that a seal 610 may be formedbetween the expandable housing 614 and the diaphragm 600. As can also beseen in FIG. 17, rim 606 of diaphragm 600 has a greater thickness thandiaphragm body 604. The greater thickness of rim 606 may aid in creatingthe seal 610 between the rim 606 and interior surface 612 of theexpandable housing during the pump stroke, while still allowing fordiaphragm body 606 to have the flexibility necessary for collapse duringthe fill stroke. In this variation, the conical shape of the diaphragmhelps to seal the diaphragm against the interior surface 612 and alsoprevent eversion of the diaphragm when pressure from blood flow (in thedirection of arrows) pushes against it.

In some variations, the flexible diaphragm may comprise one or more(e.g., a plurality, two, three, four, five, six or more) ribs. Referringto the cross-sectional view provided in FIG. 16C, a plurality of ribs608 may extend from a center portion 601 of the diaphragm body 604 tothe rim 606. The plurality of ribs 608 may be employed to maintain theconical shape of the diaphragm body 604 during a pump stroke. Theplurality of ribs 608 may have a rib angle between the longitudinal axisof each rib and an axis perpendicular to the actuator of about 60degrees. Although the plurality of ribs 608 are shown as equally spacedfrom one another, in some instances they may be spaced unequally fromone another.

Instead of a flexible diaphragm, the pumps may include a valve cone asthe linearly reciprocating valve member. In one variation, asillustrated in FIGS. 25A to 25C, the valve cone 1200 may include anexpandable frame 1202, a mesh cone 1204, and a flow control cone 1206.Flow control cone 1206 includes a plurality of arc shaped flaps 1212.Other flap shapes may also be used. Additionally, although theexpandable frame 1202, mesh cone 1204, and flow control cone 1206 areshown as conically shaped, they may be formed to have a different shape.Expandable frame 1202 may be a stent-like structure having an expandedconfiguration at one end and a collapsed configuration. In the expandedcone shape shown in the figures, the expandable frame 1202 contains themesh cone 1204 and the flow control cone 1204 within the cone 1208 ofthe frame 1202. The flow control valve 1200 may be generally configuredsuch that the mesh cone 1204 sits between the flow control cone 1206 andthe expandable frame 1202. In this configuration, the plurality of flaps1212 open in the direction of arrow A when blood is pulled through themesh cone into the expandable housing during the fill stroke, and closewhen blood is moved out of the expandable housing in the direction ofarrow B during the pump stroke, as illustrated in FIG. 25B. The meshcone 1204 may be disposed between the flow control cone 1206 and theexpandable frame 1202 to provide support to the flaps 1212 of the flowcontrol cone 1206 such that when pressure against the flaps 1212 isapplied during the pump stroke, the flaps 1212 are not pushed or bentthrough the openings 1201 in the expandable frame 1202. Thus, the meshcone 1204 may help maintain the flaps 1212 in the closed configurationduring the pump stroke when blood is moved out of the housing via thehousing outlet. However, during the fill stroke, the mesh cone 1204permits blood to flow from the housing inlet through the holes in themesh and then through the flaps 1212, transitioning them to their openconfiguration so that blood may move to the outlet side of the valvecone. The mesh cone 1204 and flow control cone 1206 may be stitched tothe expandable frame 1202 at multiple attachment points 1210, as shownin FIG. 25C. Other mechanisms of attaching the material layers to theexpandable frame may also be employed.

The expandable frame 1202 is shown separately from the rest of the valvecone depicted in FIGS. 26A to 26C. FIG. 26A provides a perspective viewof the expandable frame 1202, FIG. 26B provides a side view of the frame1202, and FIG. 26C provides a top view of the frame 1202. As shown inthe figures, expandable frame 1202 may include a first end 1214 and asecond end 1216. The first end 1214 may be coupled to an actuator forreciprocating the valve cone back and forth within the housing. Thesecond end 1216 is generally expandable to form a shaped end, forexample, cone shape 1208. The expandable frame 1202 may comprise aplurality of cells 1218, which may be diamond shaped. However, the cellshape is not so limited, and they may have any suitable shape. Inaddition, the cells may have any suitable size. In one variation, thecells may be sized smaller than the flaps in the flow control cone sothat the flaps are not pushed through the cells during the pump stroke.

In FIGS. 27A and 27B, the mesh cone 1204 is shown separately from therest of the valve cone depicted in FIGS. 25A to 25C. Referring to FIG.27A, the material of mesh cone 1204 may first be provided as a circularlayer 1220 with a center cut out 1222 and a slit 1224 extending from thecut out 1222 to the periphery of the circle 1226. The slit 1224 providesa free edge so that the circular layer 1220 may subsequently be rolledto form mesh cone 1204. The cone shape of the mesh cone 1204 may be heldby stitching, heat sealing, gluing, etc., the mesh material. The height(H) of the mesh cone 1204 may be between about 1.0 cm to about 2.0 cm,including all values and sub-ranges therein. For example, the height ofthe mesh cone may be about 1.0 cm, about 1.1 cm, about 1.2 cm, about 1.3cm, about 1.4 cm, about 1.5 cm, about 1.6 cm, about 1.7 cm, about 1.8cm, about 1.9 cm, or about 2.0 cm.

FIGS. 28A to 28C depict the flow control cone 1206 separately from therest of the valve cone depicted in FIGS. 25A to 25C. Referring to FIG.28A, the material of flow control cone 1206 may first be provided as acircular layer 1228 with a center cut out 1230 and a slit 1232 extendingfrom the cut out 1230 to the periphery of the circle 1234. The slit 1232provides a free edge so that the circular layer 1228 may later be rolledto form flow control cone 1206. Next, the flaps 1212 may be formed bylaser cutting or stamping the flap shapes into the circular layer 1228.The flaps 1212 are shown as arc shaped in the figures, but may have anysuitable size and shape, as previously stated. Referring to FIG. 28B, arim 1236 may be created at the periphery of the circular layer 1228 byrolling the edge of the layer upon itself to create thickness at theperiphery 1234, and then stitching, heat sealing, gluing, etc., therolled edge to maintain the thickness in that area. After the rim 1236is formed, the free edge of the slit 1232 is rolled to shape thecircular layer 1228 into flow control cone 1206. The rim 1236 may helpcreate a seal between the flow control cone 1206 and the interiorsurface of the housing during the pump stroke. The cone shape flowcontrol cone 1206 may be held by stitching, heat sealing, gluing, etc.,the mesh material. The height (H) of the flow control cone 1204 may bebetween about 1.0 cm to about 2.0 cm, including all values andsub-ranges therein. For example, the height of the flow control cone maybe about 1.0 cm, about 1.1 cm, about 1.2 cm, about 1.3 cm, about 1.4 cm,about 1.5 cm, about 1.6 cm, about 1.7 cm, about 1.8 cm, about 1.9 cm, orabout 2.0 cm.

In some variations, the pump may include an expandable housingcomprising a plurality of openings or perforations in a body thereof, aspreviously mentioned. The openings may be through-wall openings in thebody (e.g., through both the scaffold and layer), such that blood fromthe chamber of the body of the expandable housing may flow directly fromwithin the chamber to outside of the chamber, without passing backthrough the inlet or through the outlet. When openings are included, askirt may be coupled to or extend from an external surface of theexpandable housing in a manner that surrounds, overlies or otherwisecovers the plurality of openings to direct the blood flowing through theopenings. For example, the skirt may be configured to generateretrograde blood flow directed toward the patient's heart during thepump stroke of a pumping cycle. The retrograde blood flow may helpprovide adequate perfusion of arteries branching from the aortic arch,for example, the carotid arteries and subclavian arteries.

Turning to FIG. 19, pump 800 may include an expandable housing 802including a plurality of openings 804 and a cylindrical skirt 806coupled to expandable housing 802 in a manner that spaces it therefrom.The skirt 806 may be coupled to and circumferentially (or partiallycircumferentially) surround an external surface of the housing 802, andmay overlie at least a portion of the plurality of openings 804. Theskirt 806 may be comprise a first diameter at its proximal end and asecond larger diameter at its distal end, such that skirt 806 may becoupled to housing 802 at its proximal end, but then may be flared orspaced apart from the plurality of openings 804 formed in housing 802 toallow the retrograde flow of blood therethrough. Skirt 806 andexpandable housing 802 may be integrally formed as a single piece, orthey may be separate components coupled to one another by friction fit,an adhesive, welding, soldering, and/or the like. At the proximal end801 of the expandable housing 802, an outlet 808 may be provided foranterograde blood flow to the body. A cannula 810 may be coupled toexpandable housing 802 and may extend from the distal end of the housing820 through the aorta 816 and aortic valve 822 into the left ventricle814. At the distal end 824 of cannula 810, an inlet 812 for blood entryfrom the left ventricle 814 may be provided. The cannula may havevarying lengths. Varying lengths may be used to accommodate such factorsas different patient anatomy, patient size or age, desired location ofpump placement, and/or point of access to the circulatory system.Although any suitable length may be utilized, the cannula may have ashort, medium, or long length, as previously described. In FIG. 19,cannula 810 has a medium length, which ranges from about 25 cm to about30 cm.

Referring to FIG. 20, an enlarged view of pump 800 of FIG. 19 is shown.A cut out is provided in the expandable housing 802 to further show thestructure and configuration of skirt 806 in relation to the plurality ofopenings 804. In FIG. 20, housing 802 includes a plurality of openings804 at its distal end 820. Skirt 806 is concentrically disposed aboutthe expandable housing 802 and overlies the plurality of openings 804.Additionally, skirt 806 is configured such that a space 805 is providedbetween the plurality of openings 804 and the skirt 806. In use, asflexible diaphragm 803 is moved toward outlet 808, blood withinexpandable housing 802 is pushed in the direction of arrow 826 throughoutlet 808 of expandable housing 802 and toward the feet of the patient.During movement of the flexible diaphragm 803, a first portion of bloodis pushed through the plurality of openings 804 as the flexiblediaphragm passes by them. The first portion of blood is pushed intospace 805 and then directed by skirt 806 back toward the heart in thedirection of arrows 828. As the flexible diaphragm 803 continues to movetoward outlet 808, the portion of blood (second portion) remaining inthe expandable housing 802 is pushed through outlet 808 toward the feetand to the rest of the body. The combination of the number of openingsand the diameter of each opening may provide an amount of open surfacearea on the expandable housing for retrograde blood flow. Additionally,the skirt may be configured to adjust the amount of open surface areafor retrograde flow by adjusting the number of patent (open) and closedopenings. In general, a larger amount of open surface area may providemore retrograde blood flow toward the head of the patient, and a smalleramount of open surface area may provide a greater amount of anterogradeblood flow to the body.

The pumps described herein may be driven by an external linear motordrive and linear motor controller situated at the end of a catheterexternal to the patient. The linear motor drive may be operativelycoupled to the pump by a flexible cable or other flexible actuatorrunning through the catheter. For example, as shown in FIG. 22A, pump900 may be coupled to a linear motor drive 902 and linear motorcontroller 904 via catheter 906. Linear motor drive 902 and liner motorcontroller 904 may be situated outside the patient, within console 908.Catheter 906 may be coupled to the expandable housing 910 of pump 900,as shown in the close-up view in FIG. 22B. Here expandable housing 910includes a plurality of openings 914 and a skirt 912 concentricallydisposed about the openings 914. A cannula 916 may extend from theexpandable housing 910 such that a distal end 918 of the cannula 916 maybe positioned in the left ventricle 920. As shown in the close-up viewin FIG. 22C, an inlet 922 may be provided at the distal end 918 ofcannula 916. Inlet 922 may pull blood from the left ventricle 920 andinto expandable housing 910 for pumping systemically. The linear motorcontroller 904 may further be configured to control pump 900. In somevariations, linear motor controller 904 may be configured to controlpump 900 via sensor feedback, such as, for example, pressure sensorfeedback. For example, as described above, one or more pressure sensors(not shown) may be mounted in or on inlet 922 of cannula 916, and one ormore pressure sensors may be mounted in or on outlet 924 of expandablehousing 910. In some variations, two pressure sensors may be mounted inor on the inlet 922 and/or outlet 924 for redundancy. For example,referring to FIG. 24A, pump 1100 may include two pressure sensors 1102on the distal end of an inner sheath 1103 at the pump outlet 1104, andanother two pressure sensors 1106 may be disposed on a nose cap 1105 atthe pump inlet 1108. FIGS. 24B and 24C show enlarged views of thepressure transducers at the pump outlet 1104 and pump inlet 1108. Thecontroller 904 may be configured to have predetermined high and lowblood pressure set points. When measurements from the pressuretransducers indicate that blood pressure has dropped below the low setpoint, the controller 904 may increase the speed of the linearreciprocation, and/or when measurements from the pressure transducersindicate that blood pressure has increased above the high set point, thecontroller 904 may decrease the speed of the linear reciprocation tothereby reduce flow and return blood pressure back within a targetrange.

Turning to FIGS. 23A-23C, in some variations, a pump may be disposedexternal to the body, for example, within a console at the patient'sbedside. A coaxial catheter may be coupled to the pump at one end andinserted into the patient at the other end so that blood flows betweenthe patient and the external pump. The coaxial catheter may include aninflow lumen and an outflow lumen. Similar to that described for FIG.22A, an external pump may be driven by a linear motor drive and linearmotor controller situated at the end of the coaxial catheter external tothe patient. The linear motor drive may be operatively coupled to thepump by any suitable connector or fitting, e.g., a quick connectcoupler. For example, as shown in FIG. 23A, external pump 1000 may becoupled to a coaxial catheter 1006 via inlet and outlet tubes 1016. Pump1000 may also be coupled to a linear motor drive 1002 and linear motorcontroller 1004 within console 1008. Console 1008 may also comprise apower supply 1010, a battery 1012, and/or a user interface 1014. Thecoaxial catheter may include an inflow lumen 1018 and an outflow lumen1020, as shown in the close-up view provided in FIG. 23B. The distal endof coaxial catheter 1006 is illustrated in the close-up view provided inFIG. 23C, where blood is shown being pulled from the left ventricle 1024into inflow lumen 1018 at a pump intake end, and pushed out of outflowlumen 1020 at a pump exhaust end right above the aortic valve 1022. Thelinear motor controller 1004 may further be configured to control thepump 1000 via pressure transducer feedback, as described in more detailherein. For example, one or more pressure transducers (not shown) may bemounted in or on inflow lumen 1018, and another pressure transducermounted in or on outflow lumen 1020. In some variations, two pressuretransducers may be mounted in or on the inflow and outflow lumens forredundancy.

Methods

Methods for pumping blood using a linear reciprocating pump are alsodescribed herein. Utilizing a linear pump, as opposed to a rotary pump,may help avoid the shear forces that cause red blood cell damage, andmay pump blood in a pulsatile fashion, mimicking the natural pumpingcycle of the heart. In order for the pump to generate sufficient bloodpressure to move blood peripherally, a linearly reciprocating member maybe configured such that a seal is created between it and the pumphousing during a pump stroke of the pumping cycle. The pumps may beplaced in various parts of the circulatory system of a patient, such asthe left ventricle, the right ventricle, and the aorta. However, in someinstances it may be useful to have the pump lie external to the patient.The linear reciprocating pumps may be placed to assist with heartfailure due to, e.g., myocardial infarction, hypertension, trauma, andcardiac anomalies.

As a first step, the methods may include accessing the circulatorysystem of a patient. Access may generally be accomplished using theSeldinger technique whereby a guidewire is placed within a desiredartery or vein and the pump advanced over the guidewire to a targetlocation. Arterial access may be obtained, e.g., from the femoral arteryor the carotid artery. Arterial access may be useful when the targetlocation for the pump is the left ventricle or aorta. Venous access maybe obtained, e.g., from the femoral vein or internal jugular vein.Venous access may be useful when the target location for the pump is theright ventricle. The guidewire may be slidingly advanced through thelumen of a pump actuator such as a drive line, cable, or rod, whichlinearly reciprocates a valve member, for example, a valve cone or aflexible diaphragm, within the expandable housing of the pump.

The methods may also include advancing a pump to a target locationwithin the circulatory system of a patient, where the pump includes anexpandable housing comprising an outer surface, an interior surface, anexpanded configuration, and a collapsed configuration. The pump mayfurther include a valve member. In some variations, the valve member maybe a valve cone including a flow control layer and a mesh layer coupledto an expandable frame. In other variations, the valve member may be aflexible diaphragm comprising a diaphragm body and a rim disposed withinthe expandable housing, where the flexible diaphragm has an extendedconfiguration and a collapsed configuration. Once at the targetlocation, the expandable housing may be expanded from the collapsedconfiguration to the expanded configuration, and the valve cone or theflexible diaphragm contained therein linearly reciprocated to generate afill stroke and a pump stroke of a pumping cycle. When the pump furthercomprises a cannula, the cannula may be advanced through the aorticvalve and into the left ventricle of the patient. Non-limiting examplesof target locations for the expandable housing and flexible diaphragminclude the aortic arch, the descending aorta, the thoracic aorta, andthe abdominal aorta.

The expandable housing and the valve members (e.g., the valve cone andthe flexible diaphragm) may be in their collapsed configurations withinan outer sheath and inner sheath, respectively, during advancementwithin the vasculature. In some variations, once the expandable housinghas been positioned at the target location, the outer sheath may beretracted to allow the housing to expand from the collapsedconfiguration to the expanded configuration. In other variations, theexpandable housing may be advanced out of the housing, e.g., using apusher, thereby allowing the housing to expand from the collapsedconfiguration to the expanded configuration. The inner sheath, which maybe concentrically disposed about the valve cone or the flexiblediaphragm, may then be retracted to allow the valve cone or thediaphragm to expand from the collapsed configuration to the expanded orextended configuration. When the pump comprises a support member such asan expandable frame, withdrawal of the inner sheath may also allow theframe to expand from the collapsed configuration to the expandedconfiguration. When the pump comprises a support member such as a tinesupport, withdrawal of the inner sheath may also allow the plurality oftines to expand from the compressed configuration to the expandedconfiguration.

The pump may be reciprocated within the expandable housing under theforce of a reciprocating actuator (e.g., drive cable) to initiate asuccession of fill strokes and pump strokes. In variations where thevalve member is a flexible diaphragm, during each fill stroke of thepump, the flexible diaphragm may be collapsed, allowing blood to flowpast the diaphragm (with or without supporting tines) to fill theexpandable housing. During each pump stroke of the pump, the flexiblediaphragm may return to its extended configuration, forcing blood outfrom the expandable housing. In variations where the valve member is avalve cone including a flow control layer and a mesh layer, during eachfill stroke of the pump, the flaps in the flow control layer open andthe openings in the mesh allow blood to flow through the valve cone tofill the expandable housing. During each pump stroke of the pump, theflaps return to their closed configuration and are supported by the meshlayer to remain closed against the pressure of the blood as the blood isforced out of the expandable housing. The reciprocating motion of thedrive cable and pulsatile pump may be controlled by a programmablelinear motor controller to provide the desired blood flow and pressurecharacteristics. In some variations, the linear motor controller may beconfigured to control the pump via sensor (e.g., pressure transducer)feedback as described in more detail herein.

During the pump stroke, contact between the rim of the valve cone orflexible diaphragm and the inner surface of the expandable housing maybe maintained such that a seal is created to prevent blood flow betweenthe rim and interior surface. Additionally, during the pump stroke,blood may be pulled into the expandable housing. Depending on thevariation of pump used, blood may be pulled into the expandable housingfrom the left ventricle or the aorta. The pump stroke may generally pushblood out of the expandable housing into a portion of the aorta, forexample, the ascending aorta or the descending aorta. When theexpandable housing and flexible diaphragm are situated outside thepatient, blood may be pushed through the coaxial catheter coupledthereto to the ascending aorta, right above the aortic valve. During thepumping cycle, the valve cone or the flexible diaphragm may be collapsedto the collapsed configuration during the fill stroke and expanded tothe expanded or extended configuration during the pump stroke.

The pump may be advanced and positioned in various parts of thecirculatory system of the patient. In one variation, the pump may beadvanced until the expandable housing and pulsatile portion of the pump(e.g., the flexible diaphragm with or without tines) is located withinthe left ventricle and a cannula extending from the proximal end of theexpandable housing extends through the aortic valve. In this variation,blood may flow through a proximal inlet of the expandable housing tofill the expandable housing during the fill stroke (rearward movement ofthe flexible diaphragm toward the feet). Blood then exits a distaloutlet of the expandable housing to provide blood to the body during thepump stroke (forward movement of the flexible diaphragm toward thehead).

For example, as illustrated in FIG. 2, a pump 10 may be advanced in itscollapsed configuration within a patient's aorta to the left ventricle.Heart 50 includes a left ventricle 56, which fluidly communicates withan ascending aorta 52 and a descending aorta 51. Ascending aorta 52further supports a plurality of arteries such as arteries 53(brachiocephalic artery), 54 (left common carotid artery), and 55 (leftsubclavian artery). In FIG. 2, pump 10 is advanced to the left ventriclethrough the descending aorta 51 in the direction of arrow 35. Asdescribed above, pump 10 may include an outer sheath 11 through which adrive cable 40 may pass. As also described above, pump 10 may define anend 12 within which a bearing 13 may be supported. An expandable housing25 (better seen in FIG. 3) may be deployed from the outer sheath 11 andmay also fixedly support bearing 13. Tine support 15 including aplurality of tines 20 may be coupled to the end of drive cable 40 andmay be captivated within an outer sheath 11 in the manner set forthabove in FIG. 1.

Once pump 10 is positioned within the left ventricle 56, it assumes theoperational position shown in FIG. 3. Here expandable housing 25 hasbeen expanded to its expanded configuration and thus is shown to includea distal inlet (mesh portion) 26 and a proximal outlet (mesh portion)27. Proximal outlet 27 is provided at the end of the cannula (housingextension) 28 extending from the expandable housing 25 and through theaortic valve into the ascending aorta 52. With this configuration, bloodis pulled into the expandable housing 25 from the left ventricle 56during the fill stroke, and moved out of the expandable housing 25 inthe direction of the arrows to the ascending aorta 52 and arteries 53,54, and 55 during the pump stroke.

The pumping action of pump 10 may be undertaken by activating the linearmotor 19 (seen in FIG. 1) to initiate a reciprocating action of tinesupport 15 (and the plurality of tines 20) by successive forces pushingand pulling on flexible cable 40. The pumping action of pump 10 is setforth below in FIGS. 8 and 9 in greater detail. However, suffice it tonote here that FIG. 3 generally illustrates the operation of pump 10during a pump stroke, which is characterized by a pulling force upondrive cable 40 and movement of the tine support 15 in the directionindicated by arrow 36. During this pump stroke, it will be noted thatdiaphragm 30 has extended to its fully open configuration and thusexerts a driving force against blood within expandable housing 25,forcing blood upwardly through cannula (housing extension) 28 andoutwardly through proximal outlet (mesh portion) 27, and creating bloodflow through ascending aorta 52 and outwardly to the patient's bodythrough arteries such as arteries 53, 54 and 55. Referring to FIG. 4, itwill be noted that a push force against drive cable 40 in the directionindicated by arrow 37 therein produces a fill stroke during whichdiaphragm 30 is collapsed and blood flows into expandable housing 25through distal inlet 26.

With cardiac assist pulsatile pump 10 remaining positioned within theleft ventricle and aorta and expandable housing 25 remaining configuredfor operation, the pumping action of pump 10 continues as linear motor19 (seen in FIG. 1) continues the reciprocating action of tine support15 (and the plurality of tines 20) by successive forces pushing andpulling on flexible cable 40. Once again it will be understood that thepumping action of pump 10 is set forth below in FIGS. 8 and 9 in greaterdetail. However, suffice it to note here that FIG. 4 illustrates theoperation of pump 10 during a fill stroke characterized by a pushingforce upon drive cable 40 moving tine support 15 in the directionindicated by arrow 37. During this fill stroke, it will be noted thatdiaphragm 30 has partially collapsed and thus exerts a reduced forceagainst blood within expandable housing 25. As a result, blood is ableto flow inwardly through distal inlet (mesh portion) 26 filling theinterior of expandable housing 25. For purposes of illustration, andwith temporary return to FIG. 3, it will be recalled that a pull forceagainst drive cable 40 in the direction indicated by arrow 36 thereinproduces a pump stroke during which diaphragm 30 is expanded and bloodflows outwardly from expandable housing 25. Accordingly, withsimultaneous reference to FIGS. 3 and 4, the pumping action of pump 10may be illustrated by alternating the pump stroke shown in FIG. 3 andthe fill stroke shown in FIG. 4.

Some pump variations do not include a cannula extending from theexpandable housing. For example, pump 100 in FIGS. 5, 6 and 7, issubstantially identical to pump 10 in FIGS. 3 and 4 both in structureand function, except for the lack of cannula (extended portion) 28. Inaddition, as shown in FIGS. 18 A and 18B, pump 700 does not include acannula extending from either the proximal end 702 or distal end 704 ofthe expandable housing 710, but is otherwise substantially identical topump 100. Exemplary target locations for pumps 100 and 700 may be thethoracic aorta 706 (FIG. 18A) or the abdominal aorta 708 (FIG. 18B). InFIG. 5, blood from one portion of the aorta enters the expandablehousing 60 via inlet 63 and is pumped to a second portion of the aortaupon exiting outlet 64 of the expandable housing 60. Referring to FIG.18A, blood from one portion 716 of the thoracic aorta 706 enters theexpandable housing 710 via inlet 712 and is pumped to a second portion718 of the thoracic aorta 706 upon exiting outlet 714 of the expandablehousing 710. In FIG. 18B, blood from one portion 720 of the abdominalaorta 708 enters the expandable housing 710 via inlet 712 and is pumpedto a second portion 722 of the abdominal aorta 708 upon exiting outlet714 of the expandable housing 710.

By way of overview, FIGS. 5, 6 and 7 set forth sequential section viewsof the pulsatile pump 100 illustrating the transition of the pulsatilepump portion between its compacted configuration utilized duringcatheter insertion and its expanded operational configuration utilizedduring pumping action. Thus, FIG. 5 shows a section view of linearcardiac assist tile pump 100 in its collapsed configuration while FIG. 7shows a section view of pump 100 in its expanded operationalconfiguration. FIG. 6 sets forth a section view of pump 100 at a pointintermediate between the configurations shown in FIGS. 5 and 7.

FIGS. 8 and 9 set forth section views of pump 100 in operation. FIG. 8sets forth a section view of pump 100 during a fill stroke while FIG. 9sets forth a section view of pump 100 during a pump stroke. Thesuccession of fill and pump strokes are carried forward on a repeatedbasis to produce pulsatile pumping action as the linear motor (linearmotor 19 seen in FIG. 1) reciprocates drive cable 40 and therebyreciprocates the pumping mechanism within pump 100.

With specific reference to FIG. 8 pump 100 includes an expandablehousing 60 having an end 62 supporting a bearing 13 and inlet (scaffoldportion) 63. Expandable housing 60 further includes a chamber 61 and anoutlet (scaffold portion) 64. The chamber may be formed by embedding aportion of the scaffold of expandable housing 60 within a polymer layer(e.g., overmolding) or coupling a fabric layer to the scaffold, aspreviously described. Tine support 15 may be slidably received withinbearing 13 and joined to the interior end of a drive cable 40. Tinesupport 15 supports a plurality of tines 20 and a flexible diaphragm 30.Tine support 15 may define a plurality of outwardly extending splineribs between which spline grooves are formed. The spline grooves provideblood flow paths by which blood is able to flow past tine support 15.

As mentioned, FIG. 8 shows a fill stroke in the operation of pump 100.Accordingly, the reciprocating force applied to drive cable 40 movestine support 15 in the direction indicated by arrow 38. Because blood ispresent within chamber 61, the movement of tine support 15 in thedirection indicated by arrow 38 causes a force against the back side ofdiaphragm 30 which in turn flexes it in the manner shown. The flexing ofdiaphragm 30 away from its outwardly extended position (seen in FIG. 9)allows blood flow around tines 20 and diaphragm 30 within chamber 61.This provides a filling of chamber 61 with blood drawn through inletportion 63 and bearing 13. Once tine support 15 reaches the end of itsfilling stroke, the drive apparatus described above applies a pullingforce to drive cable 40 initiating a pump stroke shown in FIG. 9.

With specific reference to FIG. 9 pump 100 includes an expandablehousing 60 having an end 62 supporting a bearing 13 and an inlet(scaffold portion) 63. Expandable housing 60 further includes a chamber61 and an outlet (scaffold portion) 64. Tine support 15 is slidablyreceived within bearing 13 and is joined to the interior end of a drivecable 40. Tine support 15 includes a plurality of tines 20 and aflexible diaphragm 30. Tine support 15 defines a plurality of outwardlyextending spline ribs between which spline grooves are formed. Thespline grooves provide blood flow paths by which blood is able to flowpast tine support 15.

As mentioned, FIG. 9 shows a pump stroke in the operation of pump 100.Accordingly, the reciprocating force applied to drive cable 40 movestine support 15 in the direction indicated by arrow 39. Because blood ispresent within chamber 61, the movement of tine support 15 in thedirection indicated by arrow 39 causes a force against the front side ofdiaphragm 30 which in turn forces diaphragm 30 against tines 20 theextended position shown. The extension of diaphragm 30 to its outwardlyextended position forces blood from chamber 61 ahead of diaphragm 30 asdiaphragm 30 moves in the direction indicated by arrow 39. This in turncreates a blood flow outwardly from chamber 61 through outlet 64. Oncethe tine support 15 reaches the end of its pump stroke, the driveapparatus described above applies a pushing force to drive cable 40initiating the next fill stroke shown in FIG. 8. As the drive apparatusdescribed above reciprocates, alternate push and pull forces againstcable 40 are generated that correspond to successive fill and pumpstrokes of pump 100, which produce a pulsatile blood flow.

As previously described, the expandable housing in some variations maycomprise a plurality of openings and a skirt coupled to the expandablehousing. In this instance, blood exiting the openings may be directed ina retrograde direction toward the heart of the patient during the pumpstroke by the skirt. The retrograde blood flow may help provide adequateperfusion of arteries branching from the aortic arch, for example, thecarotid arteries and subclavian arteries. The ability to maintainadequate perfusion of the subclavian artery may prevent flow reversalfrom the vertebrobasilar artery to the subclavian artery, a phenomenonknown as “subclavian steal.” For example, referring to FIG. 21, pump 800may pull blood from the left ventricle 814 through inlet 812 provided atthe distal end 824 of cannula 810, which may extend from expandablehousing 802. From the inlet 812, blood may flow in the direction ofarrows 830 to fill expandable housing 802. During a pump stroke, bloodfrom the expandable housing 802 may generally be moved toward outlet 808in the direction of arrows 826. However, as blood is moved past theplurality of openings 804, a first portion of blood may be pushedthrough openings 804 and then directed by skirt 806 back toward theheart in the direction of arrows 828 to perfuse vessels 818 branchingfrom the aortic arch. The portion of blood (second portion) not pushedout of the expandable housing through the plurality of openings 804, andremaining in the expandable housing 802 is pushed through outlet 808toward the feet and to the rest of the body.

The length of the skirt may be adjusted to achieve a predeterminedamount of retrograde blood flow toward the heart of the patient.Alternatively, the number of openings may be adjusted to achieve apredetermined amount of retrograde blood flow toward the head of thepatient. The diameter of the openings may also be adjusted to achieve apredetermined amount of retrograde blood flow toward the head of thepatient. The combination of the number of openings and opening diametermay provide an amount of open surface area on the expandable housing forretrograde blood flow. Accordingly, adjustment of any one or combinationof the foregoing features may be utilized so that about 60% of the bloodfrom the pump stroke flows in a retrograde direction toward the heart ofthe patient about 50% of the blood from the pump stroke flows in aretrograde direction toward the heart of the patient, or about 40% ofthe blood from the pump stroke flows in a retrograde direction towardthe head of the patient.

In some variations, the skirt may be configured to adjust the amount ofopen surface area for retrograde flow by adjusting the number of patent(open) and closed openings. For example, a tether may be coupled to theskirt and configured to open and close the skirt against the expandablehousing similar to how a noose can be tightened and loosened. The amountof opening or closing may be adjusted using a rotatable dial disposed,e.g., on a console external to the patient. In general, a larger amountof open surface area may provide more retrograde blood flow toward thehead and heart of the patient, and a smaller amount of open surface areamay provide a greater amount of anterograde blood flow to the body.

Other methods for pumping blood may include advancing a pump to a targetlocation within the aorta of a patient, such as the thoracic aorta orthe abdominal aorta, where the pump has a fill stroke and a pump stroke;pulling a fill volume of blood into the pump during the pump stroke; andpushing an exit volume of blood out of the pump during the pump stroke,where the exit volume comprises a first portion of blood and a secondportion of blood. The fill stroke may pull blood from the left ventricleof the patient. Additionally, the first portion of blood may be pumpedin a retrograde direction toward the head of the patient, and the secondportion of blood may be pumped in an anterograde direction. The secondportion of blood may be about 60% of the exit volume, about 50% of theexit volume, or about 40% of the exit volume.

When the pump is disposed external to the patient, the method forpumping blood may include accessing the circulatory system of a patientwith a coaxial catheter. The external pump may include the same valvemember, e.g., a valve cone or a flexible diaphragm, as the internalpumps placed within the vasculature or a heart chamber, but the housingmay not be expandable. The valve cone or flexible diaphragm containedwithin the expandable housing may comprise a body and a rim. Theflexible diaphragm may have an extended configuration and a collapsedconfiguration, and the valve cone may have an expanded configuration anda collapsed configuration. The external pump may be disposed within aconsole comprising a user interface. The coaxial catheter may comprisean inflow lumen and an outflow lumen. The coaxial catheter may becoupled to the external pump at one end, and the other end inserted andadvanced within the patient.

Access to the circulatory system with a coaxial catheter may be obtainedfrom any suitable artery or vein, for example, the femoral artery, thesubclavian artery, the carotid artery, or the jugular vein. Once accessis obtained, the coaxial catheter may be advanced to a target locationin the circulatory system and the flexible diaphragm linearlyreciprocated within the housing to generate a fill stroke and a pumpstroke of a pumping cycle. During the pump stroke, contact between therim of the valve cone or the flexible diaphragm and the interior surfaceof the housing may be maintained to create a seal therebetween andprevent blood from flowing around the valve cone or the flexiblediaphragm. The seal may help generate and maintain the force of the pumpstroke as well as minimize red blood cell damage that may occur withblood flowing between a space existing between the rim and the interiorsurface. The methods described herein may include advancing a coaxialcatheter to various target locations in a patient. For example, thetarget location for the inflow lumen of the coaxial catheter may be aleft ventricle of the patient, and the target location for the outflowlumen of the coaxial catheter may be above an aortic valve of thepatient.

For example, as shown in FIG. 23A, external pump 1000 is coupled to acoaxial catheter 1006 by inlet and outlet tubes 1016. Coaxial catheter1006 includes an inflow lumen 1018 and an outflow lumen 1020, as shownin the close-up view provided in FIG. 23B. Access to the circulatorysystem by coaxial catheter 1006 is via the femoral artery 1026. Onceaccess is obtained, coaxial catheter 1006 is advanced to the leftventricle 1024. More specifically, and as shown in the close-up view ofFIG. 23C, the distal end of coaxial catheter 1006 is advanced until theinflow lumen 1018 is within the left ventricle and the outflow lumen1020 is situated above the aortic valve. In FIG. 23C, blood is shown asbeing pulled from the left ventricle 1024 into inflow lumen 1018 at apump intake end, and pushed out of outflow lumen 1020 at a pump exhaustend right above the aortic valve 1022. Pump 1000 is also coupled to alinear motor drive 1002 and linear motor controller 1004 within console1008. Console 1008 also includes a power supply 1010, a battery 1012,and a user interface 1014. The linear motor controller 1004 may beconfigured to control the speed of the pump 1000 via pressure transducerfeedback. For example, a pressure transducer (not shown) may be mountedin or on inflow lumen 1018, and another pressure transducer mounted inor on outflow lumen 1020. In some variations, two pressure transducersmay be mounted in or on the inflow and outflow lumens for redundancy incase one fails. The controller may be configured to have predeterminedhigh and low blood pressure set points. When measurements from thepressure transducers indicate that blood pressure has dropped below thelow set point, the controller 1004 would increase the speed of thelinear reciprocation, and if too high (e.g., above the high set point),the controller 1004 would slow the speed of the linear reciprocation tothereby reduce flow and blood pressure back within a target range.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the invention.However, it will be apparent to one skilled in the art that specificdetails are not required in order to practice the invention. Thus, theforegoing descriptions of specific embodiments of the invention arepresented for purposes of illustration and description. They are notintended to be exhaustive or to limit the invention to the precise formsdisclosed; obviously, many modifications and variations are possible inview of the above teachings. The embodiments were chosen and describedin order to explain the principles of the invention and its practicalapplications, they thereby enable others skilled in the art to utilizethe invention and various embodiments with various modifications as aresuited to the particular use contemplated.

1. A pump for assisting blood circulation comprising: a housingcomprising an interior surface and an expanded configuration; a valvemember comprising a rim disposed within the expandable housing, whereinthe valve member has an expanded or extended configuration, and acollapsed configuration; and an actuator coupled to the valve member,wherein the actuator is configured to linearly reciprocate the valvemember within the housing, wherein the pump has a fill stroke and a pumpstroke, and wherein the rim of the valve member is configured tomaintain contact with the interior surface of the housing during thepump stroke.
 2. The pump of claim 1, wherein the valve member comprisesa valve cone.
 3. The pump of claim 2, wherein the valve cone comprises aplurality of material layers coupled to an expandable frame.
 4. The pumpof claim 3, wherein the plurality of material layers comprises a meshlayer.
 5. The pump of claim 4, wherein the mesh layer comprises a wovenfabric.
 6. The pump of claim 4, wherein the mesh layer comprises anelastomeric polymer.
 7. The pump of claim 6, wherein the elastomericpolymer comprises a silicone, a polyester, a polyurethane, or acombination thereof.
 8. The pump of claim 3, wherein the plurality ofmaterial layers comprises a flow control layer, the flow control layercomprising a plurality of flaps having an open configuration and aclosed configuration.
 9. The pump of claim 8, wherein the flow controllayer comprises 15 flaps.
 10. The pump of claim 8, wherein the pluralityof flaps have a semi-circular shape or an arc shape.
 11. The pump ofclaim 8, wherein the plurality of flaps are in the open configurationduring the fill stroke.
 12. The pump of claim 8, wherein the pluralityof flaps are in the closed configuration during the pump stroke.
 13. Thepump of claim 8, wherein the flow control layer comprises a body, andthe rim is formed by rolling an edge of the body.
 14. The pump of claim13, wherein a thickness of the rim is greater than a thickness of thebody.
 15. The pump of claim 13, wherein the body has a thickness rangingfrom about 0.03 mm to about 0.05 mm.
 16. The pump of claim 1, whereinthe rim has a thickness ranging from about 0.20 mm to about 1.5 mm. 17.The pump of claim 3, wherein each of the layers of the plurality ofmaterial layers has a conical shape.
 18. The pump of claim 3, whereinthe expandable frame has a conical shape in its expanded configuration.19. The pump of claim 3, wherein the expandable frame comprisesstainless steel, nickel, titanium, or an alloy thereof.
 20. The pump ofclaim 13, wherein the body of the flow control layer and the rimcomprise the same material.
 21. The pump of claim 1, wherein the housingis expandable and comprises a scaffold, the scaffold comprising aproximal end and a distal end.
 22. The pump of claim 21, wherein thescaffold comprises stainless steel, titanium, or alloys thereof.
 23. Thepump of claim 21, wherein the proximal and distal ends of the scaffoldare tapered.
 24. The pump of claim 21, wherein the distal end comprisesan inlet for blood flow during the fill stroke.
 25. The pump of claim21, wherein the proximal end comprises an outlet for blood flow duringthe pump stroke.
 26. The pump of claim 1, wherein the housing has adiameter ranging from about 12 mm to about 20 mm in the expandedconfiguration.
 27. The pump of claim 1, further comprising a cannula.28. The pump of claim 27, wherein the cannula extends from the proximalend of the expandable housing.
 29. The pump of claim 27, wherein thecannula extends from the distal end of the expandable housing.
 30. Thepump of claim 27, wherein the cannula has a length of about 2.5 cm toabout 5.0 cm.
 31. The pump of claim 27, wherein the cannula has a lengthof about 25 cm to about 30 cm.
 32. The pump of claim 27, wherein thecannula has a length of about 35 cm to about 40 cm.
 33. The pump ofclaim 1, wherein the housing further comprises a polymer layer.
 34. Thepump of claim 33, wherein the polymer layer comprises an elastomericpolymer.
 35. The pump of claim 34, wherein the elastomeric polymercomprises a silicone, a polyester, a polyurethane, or a combinationthereof.
 36. The pump of claim 21, wherein the housing further comprisesa fabric layer coupled to the scaffold.
 37. The pump of claim 36,wherein the fabric layer comprises a woven material.
 38. The pump ofclaim 1, wherein the valve member comprises a flexible diaphragm, theflexible diaphragm comprising a diaphragm body.
 39. The pump of claim38, wherein the flexible diaphragm comprises an elastomeric polymer. 40.The pump of claim 39, wherein the elastomeric polymer comprises asilicone, a polyester, a polyurethane elastomer, or a combinationthereof.
 41. The pump of claim 38, wherein the diaphragm body and therim comprise the same material.
 42. The pump of claim 38, wherein thediaphragm body and the rim are integrally formed.
 43. The pump of claim42, wherein a thickness of the rim is greater than a thickness of thediaphragm body.
 44. The pump of claim 38, wherein the diaphragm body hasa thickness ranging from about 0.03 mm to about 0.3 mm.
 45. The pump ofclaim 38, wherein the rim has a thickness ranging from about 0.20 mm toabout 1.5 mm.
 46. The pump of claim 38, wherein the flexible diaphragmis in the collapsed configuration during the fill stroke.
 47. The pumpof claim 38, wherein the flexible diaphragm is in the extendedconfiguration during the pump stroke.
 48. The pump of claim 38, whereinthe flexible diaphragm has a conical shape in the extendedconfiguration.
 49. The pump of claim 48, wherein the flexible diaphragmcomprises a plurality of ribs that extend from a center portion of thediaphragm body to the rim.
 50. The pump of claim 49, wherein a rib anglebetween a rib of the plurality of ribs and an axis perpendicular to theactuator ranges from about 30 degrees to about 60 degrees.
 51. The pumpof claim 49, wherein the plurality of ribs are equally spaced from oneanother.
 52. The pump of claim 38, further comprising a plurality oftines coupled to the actuator that support the flexible diaphragm in theextended configuration during the pump stroke.
 53. The pump of claim 52,wherein the plurality of tines are flexible and have an expandedconfiguration and a compressed configuration.
 54. The pump of claim 1,wherein the housing comprises a plurality of openings.
 55. The pump ofclaim 54, wherein the housing comprises between about 2 to about 25openings.
 56. The pump of claim 54, wherein the plurality of openingsare equally spaced on a portion of the housing.
 57. The pump of claim54, wherein the plurality of openings are provided in a pattern on aportion of the housing.
 58. The pump of claim 54, further comprising askirt coupled to the housing and surrounding the plurality of openings.59. The pump of claim 54, wherein the plurality of openings have adiameter ranging between about 0.10 mm to about 6.50 mm.
 60. The pump ofclaim 1, wherein the housing is disposed within a console external to apatient.
 61. The pump of claim 60, wherein a coaxial catheter is coupledto the housing.
 62. The pump of claim 61, wherein the coaxial cathetercomprises an inflow lumen and an outflow lumen.
 63. The pump of claim62, wherein the inflow lumen has a diameter greater than about 5 F. 64.A method of pumping blood comprising: advancing a pump to a targetlocation within the circulatory system of a patient, the pumpcomprising: an expandable housing comprising an interior surface, anexpanded configuration, and a collapsed configuration; a valve membercomprising a rim disposed within the expandable housing, wherein thevalve member has an extended or expanded configuration, and a collapsedconfiguration; and expanding the expandable housing from the collapsedconfiguration to the expanded configuration at the target location;linearly reciprocating the valve member within the expandable housing togenerate a fill stroke and a pump stroke; and maintaining contactbetween the rim of the valve member and the interior surface of theexpandable housing during the pump stroke.
 65. The method of claim 64,wherein the valve member comprises a valve cone, the valve conecomprising a flow control layer.
 66. The method of claim 65, wherein theflow control layer comprises a plurality of flaps having an openconfiguration and a closed configuration.
 67. The method of claim 64,wherein the valve member comprises a flexible diaphragm, the flexiblediaphragm having an extended configuration and a collapsedconfiguration.
 68. The method of claim 64, wherein the pump stroke pullsblood into the expandable housing.
 69. The method of claim 68, whereinthe blood is pulled into the expandable housing from the left ventricle.70. The method of claim 68, wherein the blood is pulled into theexpandable housing from the aorta.
 71. The method of claim 64, whereinthe pump stroke pushes blood out of the expandable housing.
 72. Themethod of claim 71, wherein the blood is pushed out of the expandablehousing into a portion of the aorta.
 73. The method of claim 72, whereinthe portion of the aorta is the ascending aorta.
 74. The method of claim72, wherein the portion of the aorta is the descending aorta.
 75. Themethod of claim 66, further comprising opening the plurality of flaps tothe open configuration during the fill stroke.
 76. The method of claim66, further comprising closing the plurality of flaps to the closedconfiguration during the pump stroke.
 77. The method of claim 67,further comprising collapsing the flexible diaphragm to the collapsedconfiguration during the fill stroke.
 78. The method of claim 67,further comprising extending the flexible diaphragm to the extendedconfiguration during the pump stroke.
 79. The method of claim 64,wherein the expandable housing is advanced through the aortic valve andinto the left ventricle of the patient.
 80. The method of claim 64,wherein the pump further comprises a cannula, and the cannula isadvanced through the aortic valve and into the left ventricle of thepatient.
 81. The method of claim 64, wherein the target location for theexpandable housing is the aortic arch.
 82. The method of claim 64,wherein the target location for the expandable housing is the descendingaorta.
 83. The method of claim 64, wherein the target location for theexpandable housing is the thoracic aorta.
 84. The method of claim 64,wherein the target location for the expandable housing is the abdominalaorta.
 85. The method of claim 67, wherein the pump further comprises aplurality of tines that support the flexible diaphragm in the extendedconfiguration during the pump stroke.
 86. The method of claim 64,wherein the expandable housing comprises a plurality of openings. 87.The method of claim 86, wherein blood exiting the openings is directedin a retrograde direction toward the head of the patient during the pumpstroke by a skirt coupled to the housing.
 88. The method of claim 87,wherein the length of the skirt is adjusted to achieve a predeterminedamount of retrograde blood flow toward the head of the patient.
 89. Themethod of claim 87, wherein the number of openings is adjusted toachieve a predetermined amount of retrograde blood flow toward the headof the patient.
 90. The method of claim 87, wherein the diameter of theopenings is adjusted to achieve a predetermined amount of retrogradeblood flow toward the head of the patient.
 91. The method of claim 87,wherein about 60% of the blood from the pump stroke flows in aretrograde direction toward the head of the patient.
 92. The method ofclaim 87, wherein about 50% of the blood from the pump stroke flows in aretrograde direction toward the head of the patient.
 93. The method ofclaim 87, wherein about 40% of the blood from the pump stroke flows in aretrograde direction toward the head of the patient.
 94. A method ofpumping blood comprising: accessing the circulatory system of a patientwith a coaxial catheter extending from a pump located external to thepatient, the pump comprising: a housing comprising an interior surface;and a valve member comprising a rim disposed within the expandablehousing; advancing the coaxial catheter to a target location in thecirculatory system; linearly reciprocating the valve member within theexpandable housing to generate a fill stroke and a pump stroke; andmaintaining contact between the rim of the valve member and the interiorsurface of the housing during the pump stroke.
 95. The method of claim94, wherein the valve member comprises a valve cone, the valve conecomprising a flow control layer.
 96. The method of claim 95, wherein theflow control layer comprises a plurality of flaps having an openconfiguration and a closed configuration.
 97. The method of claim 94,wherein the valve member comprises a flexible diaphragm, the flexiblediaphragm having an extended configuration and a collapsedconfiguration.
 98. The method of claim 94, wherein the coaxial cathetercomprises an inflow lumen and an outflow lumen.
 99. The method of claim98, wherein the inflow lumen has a diameter greater than about 5 F. 100.The method of claim 98, wherein the inflow lumen receives blood from theleft ventricle and the outflow lumen returns blood to the ascendingaorta.
 101. The method of claim 98, wherein the pump stroke pulls bloodinto the housing through the inflow lumen.
 102. The method of claim 98,wherein the pump stroke pushes blood out of the housing and through theoutflow lumen.
 103. The method of claim 96, further comprising openingthe plurality of flaps to the open configuration during the fill stroke.104. The method of claim 96, further comprising closing the plurality offlaps to the closed configuration during the pump stroke.
 105. Themethod of claim 97, further comprising collapsing the flexible diaphragmto the collapsed configuration during the fill stroke.
 106. The methodof claim 97, further comprising extending the flexible diaphragm to theextended configuration during the pump stroke.
 107. The method of claim94, wherein the circulatory system is accessed from the femoral artery,the subclavian artery, or the carotid artery.
 108. The method of claim98, wherein the target location for the inflow lumen is a left ventricleof the patient.
 109. The method of claim 98, wherein the target locationfor the outflow lumen is above an aortic valve of the patient.
 110. Themethod of claim 97, wherein the pump further comprises a plurality oftines that support the flexible diaphragm in the extended configurationduring the pump stroke.
 111. The method of claim 94, wherein the pump isdisposed within a console comprising a user interface.
 112. A method ofpumping blood comprising: advancing a pump to a target location withinthe aorta of a patient, the pump having a fill stroke and a pump stroke;pulling a fill volume of blood into the pump during the pump stroke; andpushing an exit volume of blood out of the pump during the pump stroke,the exit volume comprising a first portion of blood and a second portionof blood, wherein the first portion of blood is pumped in a retrogradedirection toward the head of the patient, and the second portion ofblood is pumped in an anterograde direction.
 113. The method of claim112, wherein the fill stroke pulls blood from the left ventricle of thepatient.
 114. The method of claim 112, wherein the second portion ofblood is about 60% of the exit volume.
 115. The method of claim 112,wherein the second portion of blood is about 50% of the exit volume.116. The method of claim 112, wherein the second portion of blood isabout 40% of the exit volume.
 117. The method of claim 112, wherein thetarget location is the thoracic aorta.
 118. The method of claim 112,wherein the target location is the abdominal aorta.